Year	Percent
1963	0.20649
1964	0.58989
1965	0.99033
1966	1.13327
1967	1.30499
1968	1.21834
1969	1.08007
1970	1.05748
1971	1.22772
1972	1.54181
1973	1.65928
1974	1.777
1975	1.8789
1976	2.48474
1977	3.74018
1978	5.19929
1979	5.50161
1980	4.51532
1981	4.22532
1982	4.57278
1983	4.19523
1984	3.47691
1985	2.37576
1986	2.50358
1987	3.13374
1988	2.94555
1989	2.74085
1990	2.88821
1991	2.35426
1992	1.90075
1993	1.83774
1994	1.64125
1995	1.64672
1996	1.41795
1997	1.34064
1998	1.22012
1999	1.18697
2000	1.31374
2001	1.50475
2002	1.63241
2003	1.6501
2004	1.61419
2005	1.69059
2006	1.45518
2007	1.54791
2008	1.61585
2009	1.56145
2010	1.55514
2011	1.54142
2012	1.66647
2013	1.56179
2014	1.33404
2015	1.33074
2016	1.33088
2017	1.23071