Before you look at the graph …
What subjects do you think have become more or less prevalent in US high schools since the late 1980s?
If we measure the percentage of all high school teachers who are assigned to each major subject, this is the pattern:
Almost all the subjects were similar in 1988 and 2012, except that vocational education dropped a lot and health/physical education shrank by a bit. The other subjects all gained about the same amounts at the expense of those two.
It isn’t worth showing the trends for most of those subjects by year, because the lines would be pretty flat. But here is the proportion of vo-tech teachers for all the years in the survey.
Posted without a comment, except to say that this may surprise people who think that some of the arts and sciences have expanded at the expense of others.
My analysis of U.S. Department of Education, National Center for Education Statistics, Schools and Staffing Survey (SASS), “Public School Teacher Data File,” 1987-88 through 2011-12; “Private School Teacher Data File,” 1987-88 through 2011-12; and “Charter School Teacher Data File,” 1999-2000.