It was the same in the '90s. Something like a third didn't make it through in 4 years, although a long tail managed it in 5 or more.

A classmate dropped out in his sophomore year, and 10 years later asked to come back and finish. Caltech said sure, and aced the courses and earned his degree.

I asked him, were you smarter after 10 years? He laughed and said nope, he was just willing to work this time!

(Another gem about Caltech - once you're admitted, they'll give you endless chances to come back and finish. Your credits did not expire.)

One of my friends finally graduated after 6 years there. He endured endless students mumbling "7 years, down the drain!" as they passed by. (The line was from Animal House.)

late 70's