Philosopher Timothy O'Connor (Indiana) calls my attention to this interesting essay.  He writes:

It provides helpful perspective on trends in student ‘majors’ in higher ed in the US, UK, and Australia from the 1950s forward. Its major theme is the relative stability of the percentage of university students studying the humanities — and so, with the rise of mass ed, large increase in their absolute numbers — in each country. (The percentage in the UK is roughly double that of the US, with Australia in between.)  A caveat is that the range of fields of study has broadened considerably in the humanities, thereby impacting enrollments in core fields such as philosophy.