| | | | | | | 1970 | 13% 40% | 1970 3% 1996 9% | 1958 1% | 2015 7.4% 6.5 | | | | | | | | | | | | | | | | | | | | | | | | | 2 | | | | | | | | | | | | | | | | | | | | | | |