Hits raise last year:
7.9% for IMRT (1982)
(last 3 years 7.1%)
2.2% for HT (1995)
(last 3 years 17.8%)
28% for IMAT (1995)
(last 3 years 26.9%)
77% for VMAT (2005)
(last 3 years 58.0%)
Evolution of interest