It's a combination of mainly two things. 1. More people are getting PhDs, which means if the job supply remained constant, higher percentages of people won't g

It's a combination of mainly two things. 1. More people are getting PhDs, which means if the job supply remained constant, higher percentages of people won't get a job. 2. There are fewer "real" academic jobs, because universities have evolved to focus on cost-cutting business practices, tenured faculty are expensive, and an endless stream of abused adjuncts has no down side except the quality of education provided by your university, and who cares about that anyway.