Here is the quick summary of the historical trends by major:
From 1970 until 2010, US population grew by about a third. However, the number of bachelor's degrees granted doubled. This is reasonable - we have a more knowledge driven economy.
There were about 52 thousand engineering and computer degrees per year around 1970. By 2010, this number is about 120 thousand - so that more then doubled. Much of this is related to computer science/information degrees (not surprising). Engineering increased but failed to double.
Math/statistics degrees decreased from about 25 thousand per year to 15 thousand per year. That might be concerning.
Physical science degrees (mostly chemistry, some geology and physics) were unchanged: about 21 thousand per year up to about 23 thousand per year. That might not sound great.
Education degrees fell from 176 thousand per year to 101 thousand per year. Ya, that is probably not good.
So what boomed? Business degrees. From 115 thousand per year in 1970 up to 358 thousand per year in 2010, which is about 22% of all degrees granted. And if you look at salary and unemployment, they do not do too bad - about on par with life science majors; better than most majors.
After business degrees, social science degrees are the next largest category, but the raw number granted per year (from 1970 to 2010) did not grow very much.
Health care related degrees, performing arts and psychology also more then doubled.