Year	Percent
1960	95.289
1961	95.328
1962	95.556
1963	95.773
1964	95.98
1965	96.177
1966	96.365
1967	96.544
1968	96.715
1969	96.877
1970	97.032
1971	97.208
1972	97.397
1973	97.573
1974	97.738
1975	97.891
1976	98.035
1977	98.169
1978	98.294
1979	98.41
1980	98.519
1981	98.655
1982	98.889
1983	99.084
1984	99.244
1985	99.377
1986	99.486
1987	99.576
1988	99.651
1989	99.712
1990	99.763
1991	99.805
1992	99.839
1993	99.867
1994	99.891
1995	99.91
1996	99.98
1997	100
1998	100
1999	100
2000	100
2001	100
2002	100
2003	100
2004	100
2005	100
2006	100
2007	100
2008	100
2009	100
2010	100
2011	100
2012	100
2013	100
2014	100
2015	100
2016	100
2017	100