Year	Percent
1965	20.79569
1966	17.8591
1967	16.29825
1968	17.5788
1969	15.91849
1970	17.03282
1971	19.38266
1972	21.45199
1973	19.7429
1974	18.72981
1975	18.47938
1976	17.75479
1977	15.81733
1978	15.08917
1979	13.54209
1980	14.13077
1981	13.66651
1982	13.15461
1983	12.37805
1984	14.21153
1985	15.81437
1986	13.01184
1987	16.46734
1988	11.83059
1989	12.91567
1990	15.72067
1991	16.7207
1992	16.12237
1993	14.70913
1994	12.55802
1995	11.36654
1996	13.7132
1997	11.2346
1998	10.60075
1999	10.60634
2000	10.00632
2001	9.42186
2002	8.29848
2003	9.2915
2004	9.90255
2005	9.16983
2006	9.28071
2007	8.64202
2008	7.84865
2009	8.45661
2010	6.84615
2011	7.57684
2012	8.30026
2013	7.96931
2014	8.57166
2015	9.20592
2016	8.52542
2017	8.98606
2018	9.88851
2019	9.76636
2020	10.38042
2021	10.13873
2022	9.84135