Year	Percent
1965	27.88346
1966	25.44223
1967	26.17136
1968	24.87356
1969	25.80311
1970	25.35908
1971	24.16725
1972	23.97418
1973	27.7144
1974	30.41049
1975	28.24639
1976	26.05301
1977	30.70562
1978	27.23065
1979	26.35334
1980	22.58957
1981	17.16634
1982	19.77326
1983	15.56106
1984	22.64445
1985	27.1725
1986	23.57752
1987	25.09054
1988	26.55154
1989	38.45677
1990	40.57802
1991	31.45596
1992	29.04676
1993	33.29869
1994	40.47779
1995	44.83493
1996	43.39834
1997	45.07675
1998	43.33726
1999	31.53988
2000	37.35972
2001	59.22953
2002	63.25224
2003	73.04184
2004	74.32844
2005	78.62355
2006	77.17505
2007	76.71676
2008	83.44246
2009	75.45214
2010	82.5654
2011	80.19674
2012	76.59151
2013	74.56483
2014	70.60759
2015	68.36735
2016	66.53359
2017	69.1269