Year	Percent
1960	16.92498
1961	16.29988
1962	13.56036
1963	13.5373
1964	15.41319
1965	16.01725
1966	14.62245
1967	17.41107
1968	15.7362
1969	15.43007
1970	11.21352
1971	13.62935
1972	11.79552
1973	15.34983
1974	14.56846
1975	22.83159
1976	23.92228
1977	22.52285
1978	23.76224
1979	19.06227
1980	19.19614
1981	26.1058
1982	19.91466
1983	12.50101
1984	7.90345
1985	8.51486
1986	10.40073
1987	14.70481
1988	12.45735
1989	16.41044
1990	17.68597
1991	23.17552
1992	23.5216
1993	24.27999
1994	17.99864
1995	24.00634
1996	25.45243
1997	35.08539
1998	36.48173
1999	21.97686
2000	19.65017
2001	36.36478
2002	27.41795
2003	35.431
2004	18.28738
2005	19.09139
2006	21.49798
2007	30.73439
2008	25.08984
2009	31.03424
2010	17.38727
2011	21.4643
2012	12.94139
2013	12.99895
2014	12.45007
2015	10.66634
2016	11.50441