Year	Percent
1970	32.62536
1971	32.62576
1972	32.62631
1973	32.62412
1974	32.61375
1975	32.63686
1976	32.62777
1977	32.62902
1978	32.61317
1979	32.56191
1980	32.75244
1981	32.58232
1982	32.63528
1983	32.53392
1984	32.3056
1985	33.70507
1986	31.73173
1987	32.90008
1988	32.02714
1989	31.16397
1990	30.23905
1991	21.93118
1992	16.91827
1993	13.19421
1994	13.23971
1995	13.40151
1996	15.3134
1997	14.9238
1998	14.25261
1999	14.53748
2000	14.13003
2001	13.23574
2002	11.52707
2003	12.95193
2004	16.02178
2005	21.01804
2006	18.71289
2007	20.33636
2008	20.56761
2009	17.45973
2010	22.57026
2011	25.10364
2012	25.511
2013	24.10043
2014	22.08388
2015	17.14739