What is now considered a 'graduate level' job though? It's certainly far more broad than it used to be. Nursing, teaching, policing, paramedic, animal care, professional cameraman or sound technician and hundreds of other jobs did not used to require a degree, and in many cases no degree specifically for those jobs even existed.
Those roles haven't suddenly become any more complicated, requiring higher levels of intelligence or more 'education' than they ever did, as far as I can tell. Yet the college based 2 year courses that were free, post 16, or the practical workplace training that you previously did while earning money, not paying it out, has been shifted to the university classroom. This 'education' has been adapted to make it last three years, often by padding it out with unnecessary, theory based flannel.
Also, when I left school, it was not only possible, but actually very common to leave school at 16 or 18 and get a job in a bank, or an advertising agency, or an oil company or whatever, on the lowest rung of the ladder and work up.
Whereas I imagine that most entrants going into corporate positions now, even at the most junior trainee level, are graduates. There are probably no more truly 'graduate level' jobs than there ever were. They haven't suddenly jumped from 5 or 7% of jobs for young people starting out in full time work, to around 35 or 40%.
It's just that the sort of young people who have the right suitability for those positions are now going to university first, then being recruited as graduates, 3 years older with a ton of student debt. The whole landscape for workplace entrants has shifted. As degrees become more ubiquitous among young people, so employers tend to assume that those who don't go to uni are either are not of the right calibre, or are more attracted/suited to vocational or trades based careers. So I suspect they are specifying graduate applicants when it's honesly not necessary to do so, and the same position (or its nearest equivalent) 25 years ago would have merely required some A levels or a year or two on a BTEC at most. Sometimes not even that.
Even then, if your figures are correct and these are genuine graduate level jobs, that still means 2.5 in 10 young people are leaving university and ending up in work that justifies neither the time and the money they spent doing it.