The percentage of students securing higher grades in the Leaving Cert has increased dramatically in every one of the 10 most popular subjects since 1989.
The new figures will raise fresh concerns that the exam is being "dumbed down" - but teacher unions last night said this charge was grossly unfair to students who, they said, were working harder than ever.
The figures from the State Exams Commission show a surge in the number of students gaining an honour (Grade C or higher) in higher level papers since 1989.
The key features include: Irish - a 24 per cent increase in the number securing honours over the past 17 years; maths - a 22 per cent increase in the honours rate over the same period; and English - a 20 per cent increase in the honours rate.
Separate figures show that the number of students failing higher- level subjects has also dropped from 13,000 in 1989 to 8,000 in 2004.
The honours rate has also risen significantly in art (up 20 per cent), geography (also up 20 per cent), home economics (up 15 per cent), business (up 15 per cent), history (up 16 per cent) biology (up 11 per cent) and French (up 6 per cent).
The increased Leaving Cert grades are reflected in CAO trends. These show a huge increase in the number of students gaining 300 points or more, up from 41 per cent to more than 55 per cent in the past decade.
Last night a leading campaigner against "grade inflation" said the new figures provided clear evidence of dumbing down.
Dr Martin O'Grady of the Institute of Technology in Tralee said it was difficult to offer any rational explanation for the constantly improving grades "other than grade inflation or, to put it in simpler terms, falling standards.
"Every third-level academic prepared to speak honestly admits that a great many students coming through from second level now show remarkable deficiencies in literacy and numeracy and have little or no sense of the art of learning," he said. "To them, learning consists of memorising material given to them in a pre-packaged form by someone else."
However, the State Exams Commission denies any lowering of standards. It pointed out that the courses had been revised in seven of the 10 subjects since 1989, making direct comparison difficult.
Today's exam candidates, it said, are better prepared, better supported and better resourced than ever before.
Association of Secondary Teachers of Ireland general secretary John White said students were working harder and smarter than ever before. "The improved results are not evidence of dumbing down, rather they underline how our students are doing well."
He said this was backed up by an OECD study which showed Irish students fifth out of 29 OECD countries in literacy tests.
Bernie Judge, education and research officer of the Teachers' Union of Ireland, also rejected suggestions of "dumbing down". She linked the improved grades to new, more accessible courses and the "huge social expectation of students to progress to third level".
Other education experts said the grade inflation could be traced to better study skills by students and the boom in the so-called "grinds culture".
