1. Rising college costs have massively outpaced inflation in the last 2 decades [0]
2. Salaries for tenured professors have not seen anything even close to that kind of growth in the same time period [1]
3. Most institutions actually employ fewer full-time faculty than they did 20 or 30 years ago, shifting more and more to part-timers and adjuncts who get paid a pittance [2]
So...college is massively more expensive than it's ever been, but full-time professor salaries have not risen significantly and there are actually fewer of them overall. So where has the money gone?
In the US, I don't know that there is a complete answer on that, but there are definitely some suspects:
* offsets to deal with slashed state funding (although federal funding has risen significantly in the same time period)
* university endowments
* university administrators [3]
* building sprees and tons of shiny new facilities
[0] http://www.bloomberg.com/news/articles/2014-11-13/college-tu...
[1] http://nces.ed.gov/programs/digest/d13/tables/dt13_316.10.as...
[2] http://nces.ed.gov/programs/digest/d13/tables/dt13_315.10.as...
[3] http://www.bloomberg.com/news/articles/2012-11-14/bureaucrat...