Year	Percent
1961	54.93646
1962	55.71848
1963	55.71848
1964	56.69599
1965	58.26002
1966	58.26002
1967	59.23754
1968	60.21505
1969	60.60606
1970	61.09482
1971	61.58358
1972	62.07234
1973	63.04985
1974	62.56109
1975	62.07234
1976	61.58358
1977	61.09482
1978	60.50831
1979	59.9218
1980	58.74878
1981	58.45552
1982	58.45552
1983	58.45552
1984	58.45552
1985	58.55327
1986	58.65103
1987	59.04203
1988	59.04203
1989	59.04203
1990	59.13978
1991	59.23754
1992	59.23754
1993	59.23754
1994	59.33529
1995	59.53079
1996	60.41056
1997	60.80156
1998	61.19257
1999	56.94037
2000	58.16227
2001	58.45552
2002	60.21505
2003	61.29032
2004	62.39492
2005	63.83187
2006	66.37341
2007	66.18768
2008	64.80938
2009	64.80938
2010	62.56109
2011	63.63636
2012	64.32063
2013	64.51613
2014	64.71163
2015	65.00489
2016	65.5914
2017	65.81818
2018	65.64516
2019	65.62072
2020	66.20723
2021	66.40274