In addition to the other comment, 73% is counting all grown up germans. The current generation has an university enrollment rate of about 50%. So while many older germans have basically been trained on the job, many younger once wont which is one of the reasons many younger foreign europeans now learn a job in germany as no inlanders apply.

Tradditionally we have the concept that kids can fail a grade and have to repeat it but more and more educators are not in favor of this anymore, so its more or less changing.