Year	Percent
1965	7.76508
1966	5.64481
1967	6.87451
1968	6.84511
1969	7.01315
1970	4.9042
1971	5.40389
1972	5.6611
1973	6.61049
1974	5.44972
1975	8.90109
1976	10.77383
1977	11.78819
1978	10.57166
1979	11.78483
1980	11.54126
1981	12.90145
1982	11.59158
1983	10.23104
1984	10.65245
1985	11.52921
1986	11.6623
1987	11.81328
1988	11.44717
1989	11.0676
1990	10.52731
1991	11.49075
1992	15.95973
1993	18.43296
1994	18.99394
1995	24.97316
1996	22.81758
1997	26.32784
1998	22.82205
1999	22.84847
2000	23.284
2001	22.56075
2002	17.73713
2003	15.69986
2004	16.6827
2005	14.58369
2006	13.44659
2007	12.85566
2008	12.77582
2009	12.41935
2010	9.58254
2011	8.90403
2012	10.07389
2013	10.68908
2014	11.50509
2015	11.62194
2016	9.49254
2017	9.7582