Germany's economic crisis is encouraging grade inflation as students demand good grades to help them compete in a tough job market.
Professors say they feel under pressure to award inflated grades - Kuschelnoten (cuddle grades) - to help their students find employment.
German firms make initial selections based on grades in a climate of widespread joblessness.
Gregor Schöllgen, professor of history at the University of Erlangen, said:
"We are getting more and more students who just finished high school - they're not all good, but they must be kept busy for several years so they're not unemployed. One day they'll need a job, but they need good grades or they have no chance."
A study by the German Scientific Commission found that either students have become very smart or professors very generous. Almost all graduates in many disciplines leave university with good or very good marks.
Grades are not distributed evenly along a scale of 1 (excellent) to 5.
Scores range from "good" to "excellent", with only a handful "satisfactory" or "sufficient".
In biology, less than 1 per cent graduated with a "satisfactory" in 2000 (the most recent year for which results are available in the three-year survey). The total of all grades in biology, physics, psychology, maths, philosophy and chemistry averaged 1.45, or "very good".
Heinz Mehlhorn, chairman of the German Biology Symposium, blamed the relationship that professors in certain disciplines have with students they want to attract, keep and possibly cultivate to progress into academe.
"When [a professor] knows a student well, there are psychological reasons at play because he doesn't want to do harm," he said.
In contrast, medicine and law graduates take written exams and have among the lowest averages.
But even among faculties typically awarding high grades there is resistance to Kuschelnoten .
Freiburg university's chemistry department gave only a "satisfactory" to more than 25 per cent of graduates in 2000. Chemistry professor Bernhard Breit said: "It's tradition here. Each professor tries to use the whole breadth of the scale."
Employers know how individual professors grade, according to Martin Suhm, professor of chemistry at the University of Göttingen. All Göttingen's chemistry graduates had a perfect 1.0 in 2000. In a bid to make his own grading more transparent, Professor Suhm publishes the results online. "I know one man can't do it alone, but that's my attempt to change it."