In the first four years of our current economic boom, the years between 1993 and 1997, employment in the State increased annually by an average of just under 50,000 a year, an annual increase of almost 4 per cent. As more than 30,000 people retire each year, that meant that over 80,000 people were entering employment annually.
That rate of job growth was remarkable, especially at a time when in the rest of the EU employment was rising by little more than one-quarter of 1 per cent a year. During these years, with much less than 1 per cent of the EU workforce, we were in fact providing one-tenth of all the additional jobs in the entire EU.
But what is absolutely astonishing is that between spring 1997 and spring 1999 employment rose by almost 90,000 a year, an annual rate of nearly 6.5 per cent. In other words, during this two-year period there was an annual flow of over 120,000 people into employment.
Where on earth did these extra workers come from? Can we possibly go on expanding our workforce at this rate, or were there temporary factors at work in those two years which will not endure?
These are crucial questions: on the answers to them may depend our capacity to emerge from this phase of our economic growth without an inflationary bubble bursting in our faces.
Depending on where these extra workers came from, a continuation of this phenomenon could have other implications, e.g. for housing, to the extent that there may have been increased numbers of immigrants; or for childcare, if they included mothers who had previously been looking after their children at home.
Or, indeed, for the future educational level of our population, if many of these were young people choosing to take up employment who would otherwise have pursued a diploma or degree.
But although so much depends on understanding the nature and components of the current flow of additional workers into employment, up to now no one seems even to have adverted to the possible long-term social and economic significance of this sudden jump in the numbers entering employment.
Part of the reason for this is that while our statistical system provides us with a regular "snapshot", little has been done to derive from this a comprehensive picture of the annual flows of people from other areas into the workforce.
Last weekend I made an attempt to assess our current employment flows, in the hope of getting some clues as to how we have been able since 1997 to increase the gross flow into employment from just under 80,000 a year up to almost 120,000 a year.
There are four possible sources of such additional workers - the education system, women at home, unemployment, and immigration. For the flow into employment to have jumped almost overnight by half after April 1997, some very significant and sudden changes must have taken place in respect, probably, of more than one of these four elements.
The easiest of these factors to tease out is unemployment. Both of the two annual Labour Survey methods of measuring employment and unemployment show that after April 1997 the annual decline in unemployment accelerated by about 15,000 a year, compared with the average unemployment decrease of the four previous years. This higher rate of decline in unemployment seems to have continued right up to the start of this year.
The accelerated fall in unemployment thus seems to account for almost two-fifths of the post-1997 increase in employment.
But this is an inherently temporary phenomenon, because inflows from unemployment into employment simply cannot continue indefinitely and must soon start to taper off: our unemployment rate has already fallen below 5 per cent, and cannot go on dropping for much longer.
Because, with 1.5 per cent of the workforce changing jobs every month - a process that can take many weeks - there must always be some people temporarily out of work. So the numbers unemployed clearly cannot fall very far below 5 per cent - certainly not below 3 per cent.
Next, there is immigration. Between 1992 and 1994 there had been net emigration by people of working age, averaging about 7,000 a year. By 1995 this had been turned around, and in that and the following year net immigration of people of working age averaged 5,000 a year. In 1997 and 1998, however, net immigration of people of working age rose to an average of about 14,000 a year.
Even allowing for some proportion of non-working spouses, this suggests an increase of perhaps 7,000 in the flow of immigrating workers in this more recent two-year period, by comparison with the two immediately preceding years.
Next, has the flow of women into the labour force also increased?
There are indications that this may be the case. The number of women working at home, including those describing themselves as "retired", has been falling for many years - by an average of 8,000 a year between 1992 and 1997. But between 1997 and 1999 this decline accelerated to an average of 13,000 a year.
However, in the absence of reliable data on the movement of women out of the labour force for childcare purposes, and back to it as the children grow up, these figures for the number of women at home can offer only a hint at what may be happening on this front.
But the biggest single source of entrants to the labour force is the education system. Are there any indications of an increase having taken place in the flow of young people emerging from the educational system?
We know how many people pass the age of 15 each year, and we also know from the Quarterly Labour Survey the total number of people who are students. From these figures we can in principle deduce how many people leave the education system each year.
It is true that this latter figure could be affected by Irish students going to study elsewhere, and by foreign students coming to study in Ireland - as well as by the arrival here of children over 14 accompanying immigrating parents.
But, taking all these factors into account, if the flow out of the educational system to employment had remained unchanged, the stock of students should have continued to rise. But the National Household Survey suggests that last year the number of female students levelled off and that the stock of male students was running below its 1998 level.
This would seem to mean that the flow from education to the labour force has suddenly increased sharply. If this is confirmed by subsequent quarterly surveys carried out last autumn and around the turn of the year, the results of which are currently awaited, this would confirm that the "pull" of employment may have started to make heavy inroads on our higher education system.
It could be that employment is drawing extra young people annually into the labour market, at the expense of the level of education they could attain.
There have been several independent indications that this may be the case. Thus, there have been signs of a fall in the number of graduates taking higher degrees. And in the past few days there have been reports in The Irish Times both of a fall in the number of mature students returning to higher education and of a rise in the post-Junior Certificate drop-out rate from second-level education.
All this should be a matter of considerable concern, for such a development, if continued, could threaten one of the key components of our movement towards a more prosperous society, namely the rapid rise in the proportion of our population which is well-educated.
At the same time, it should be made clear that, if there has in fact been a surge in the numbers moving to the labour force from the education system, such an increase can only be temporary. For the number of young people reaching the age of 18, around which time they either start work or go on to higher education, is about to fall sharply, reflecting the post-1980 decline in the birth rate.
Indeed, the number of 18-year-olds has already started to fall: it is 2,000 lower than a year ago and within the next three years there will be a further drop of 7,500 in the number of young people attaining that age.
This decline will greatly intensify the pressures that seem already to be leading towards a reversal of our 30-year-old shift towards a more educated population. It could lead both to a sharp reversal of the present temporary increase in the flow from education to the workforce, and also to an intensification of the foreshortening of educational experience of many young people.
It is obvious that we now urgently need a study in depth of just what is happening at the interface between education and employment.
To sum up then, there are indications that all four potential sources of labour have been contributing in varying degrees to the extraordinary jump in the numbers entering employment since early 1997.
But it is also clear that two of these sources - the movements from both unemployment and education into the workforce - are about to start drying up, which will greatly intensify our labour supply problem, as well as creating undesirable pressures on the crucial process of improving the educational level of our future working population.
Unless the Government faces up to the urgent need to slow what, in terms of labour supply as well as infrastructural capacity, is becoming an unsustainable rate of economic growth, and unless towards this end it stops boosting growth by inappropriate fiscal stimuli, serious trouble lies ahead for our economy.