Year	Percent
1963	2.36518
1964	3.67197
1965	5.21301
1966	6.72765
1967	11.80085
1968	10.34655
1969	11.32407
1970	10.17373
1971	10.16984
1972	10.95129
1973	11.2044
1974	12.5158
1975	13.24159
1976	19.18668
1977	15.12814
1978	21.305
1979	25.09435
1980	24.18524
1981	22.37152
1982	15.39269
1983	12.31528
1984	13.52692
1985	12.85185
1986	14.00779
1987	14.56223
1988	17.56661
1989	18.70127
1990	21.35361
1991	27.84746
1992	29.62768
1993	30.70693
1994	31.13964
1995	30.88669
1996	32.47912
1997	29.64506
1998	30.30691
1999	32.24631
2000	35.16431
2001	37.99206
2002	38.70014
2003	36.47029
2004	34.66531
2005	33.77011
2006	35.48132
2007	36.99261
2008	39.21767
2009	31.91626
2010	30.18122
2011	31.37605
2012	29.16168
2013	28.04953
2014	30.87841
2015	32.8303
2016	33.0391