Year	%
1972	27.83312
1973	32.23465
1974	34.56258
1975	35.65708
1976	37.19535
1977	32.46348
1978	38.95442
1979	37.8977
1980	39.17068
1981	38.80976
1982	44.88022
1983	43.22376
1984	44.25793
1985	43.29343
1986	47.0515
1987	47.3413
1990	47.90848
1999	31.37904
2006	44.69766
2007	58.92838
2008	49.85376
2010	57.80759
2011	61.6795
2014	65.07221
2015	63.95585