Year	Percent
1965	41.37538
1966	38.68663
1967	38.5044
1968	37.39899
1969	36.24929
1970	40.44063
1971	39.19671
1972	38.05906
1973	39.8275
1974	37.2896
1975	35.33321
1976	39.33376
1977	43.00594
1978	37.03628
1979	38.90242
1980	37.95789
1981	34.38962
1982	32.59351
1983	31.18053
1984	28.94213
1985	26.91181
1986	27.42892
1987	20.7536
1988	20.97519
1989	18.31003
1990	16.01368
1991	15.79239
1992	12.96503
1993	12.72881
1994	12.46178
1995	11.52888
1996	10.85033
1997	10.91456
1998	9.46818
1999	7.93373
2000	7.17278
2001	6.68649
2002	5.82298
2003	5.4884
2004	5.72793
2005	6.17166
2006	6.04617
2007	6.99311
2008	7.09011
2009	6.66859
2010	6.98171
2011	7.33019
2012	6.51436
2013	5.61331
2014	5.86687
2015	5.52977
2016	5.73215
2017	5.39301
2018	5.13277
2019	5.14643
2020	5.35289
2021	4.85718
2022	4.74085