Year	Percent
1965	23.24063
1966	21.9128
1967	20.33243
1968	20.32249
1969	21.30028
1970	23.23797
1971	22.23822
1972	20.57965
1973	22.22791
1974	22.15196
1975	21.47144
1976	19.04846
1977	20.06714
1978	18.72043
1979	18.67317
1980	19.75951
1981	17.85407
1982	17.06704
1983	16.10524
1984	16.51716
1985	13.10041
1986	17.36715
1987	11.86863
1988	15.7471
1989	13.82778
1990	13.42282
1991	12.50573
1992	12.01284
1993	10.7815
1994	9.99449
1995	9.81478
1996	9.1934
1997	9.1443
1998	8.99181
1999	7.82103
2000	6.71834
2001	6.99752
2002	6.80512
2003	6.69385
2004	7.02047
2005	7.21194
2006	6.85872
2007	6.51157
2008	6.33582
2009	6.13735
2010	6.05746
2011	5.63686
2012	5.40109
2013	5.30487
2014	5.19346
2015	5.4847
2016	5.50727
2017	5.34267
2018	5.14778
2019	5.22729
2020	6.04148
2021	5.66578
2022	5.78799