Year	Percent
1967	61.71762
1968	57.89335
1969	56.7748
1970	57.82877
1971	57.07616
1972	55.79488
1973	51.61128
1974	46.0558
1975	57.50932
1976	55.12434
1977	55.1771
1978	52.13693
1979	55.00662
1980	41.58998
1981	42.61274
1982	40.40048
1983	37.03898
1984	36.69367
1985	36.96282
1986	35.60661
1987	36.91423
1988	39.9456
1989	38.16033
1990	37.41768
1991	39.27466
1992	36.99633
1993	39.04665
1994	36.83569
1995	37.70895
1996	36.87921
1997	35.96217
1998	34.56067
1999	35.55572
2000	32.90187
2001	32.81361
2002	32.71418
2003	29.87663
2004	30.01551
2005	32.37848
2006	29.79051
2007	31.35287
2008	32.97032
2009	31.73571
2010	33.01683
2011	34.55863
2012	38.1141
2013	36.75282
2014	37.45677
2015	37.72326
2016	37.4037
2017	37.43244
2018	37.61244
2019	37.3078
2020	36.18804
2021	35.68183
2022	36.4213