Year	Percent
1961	60.04796
1962	60.04796
1963	60.04317
1964	59.65468
1965	59.21823
1966	58.68106
1967	58.19664
1968	57.66427
1969	57.32374
1970	56.98321
1971	58.80096
1972	58.69544
1973	58.78657
1974	59.02158
1975	59.25659
1976	58.99614
1977	59.18436
1978	60.91699
1979	63.07915
1980	63.31564
1981	61.139
1982	59.49324
1983	59.05405
1984	59.29054
1985	60.00483
1986	60.72394
1987	60.4778
1988	61.19691
1989	60.95077
1990	61.33205
1991	61.95463
1992	62.81371
1993	62.56757
1994	62.46622
1995	62.26834
1996	60.13996
1997	59.89382
1998	61.28378
1999	62.53378
2000	62.09942
2001	61.66506
2002	60.98938
2003	60.55502
2004	61.80985
2005	58.81274
2006	58.73069
2007	59.9083
2008	59.7249
2009	59.54151
2010	59.35811
2011	59.16988
2012	58.98649
2013	58.80309
2014	58.60039
2015	59.0251
2016	58.59556
2017	58.16602
2018	57.70753
2019	57.70753
2020	57.70753
2021	57.70753