While I cannot find a study on this, this may have a lot to do with the changes in university enrollment. At Yale University, the percentage of science students was 69% in the 1915-1916 school year. In the 1954-1955 school year the percentage of science students was 42.6%. 42.6% is only 61.7% of 69%. Meaning there was a reduction of science students by 38.2% in the 49 years between the two data points. The difference between an degree from the college of arts and a degree from the college of science is how the classes are taught. Science is't an ideology like the humanities so often are, it is an epistemology. In layman's terms, people with STEM degrees are taught how to find new information, while humanities are taught the truth. I have been looking for data like this for awhile, as it has been claimed that one of the reasons college degrees aren't taken seriously is because of the type of degrees being handed out. If you get a STEM degree today, you still have good outlooks for employment. I still want to find more info on this, though. I would have grabbed later data for the second point, but I couldn't find it. Yale stopped reporting how many student were enrolled in the science program in the document I was using. I used the latest data point I could and the data point 100 years ago for the analysis,