Year	Percent
1967	22.42268
1968	14.73952
1969	11.9
1970	19.66292
1971	32.13429
1972	43.75
1973	55.19481
1974	47.75726
1975	50.69045
1976	45.96857
1977	44.04308
1978	48.72687
1979	40.71345
1980	37.65549
1981	38.08878
1982	43.15168
1983	38.06708
1984	37.57918
1985	37.18279
1986	40.92647
1987	29.06705
1988	31.3537
1990	27.5991
1991	34.74133
1992	35.54794
1993	38.05479
1994	34.78751
1995	35.55614
1996	35.76596
1997	38.59102
1998	49.72464
1999	37.56279
2000	25.90459
2001	29.3343
2002	27.91514
2003	32.79556
2004	38.86952
2005	31.06016
2006	31.66428
2007	39.98937
2008	37.18064
2009	34.64604
2010	41.20986
2011	43.03652
2012	37.33984
2013	45.06952
2014	38.16674
2015	43.07428
2016	35.59158