Can't read the article, but it's about postdoc.

- Many people who did a PhD and didn't want to do research don't do a postdoc

- I would say, "40% have left so far'. Following the same cohort for a few years might yield even higher numbers (because as long you haven't made your mind about quitting research, you are still a postdoc and not accounted for leaving, even it's your 10th year...).