Year	Percent
1970	87.62887
1971	88.21293
1972	88.54296
1973	88.98409
1974	89.51807
1975	89.92891
1976	90.32634
1977	90.71101
1978	91.08352
1979	91.55556
1980	91.90372
1981	92.34914
1982	92.67516
1983	93.09623
1984	93.50515
1985	93.80081
1986	94.18838
1987	94.56522
1988	94.93177
1989	95.28846
1990	95.5408
1991	95.97001
1992	96.29972
1993	96.621
1994	96.844
1995	97.23708
1996	97.44718
1997	97.82419
1998	98.02236
1999	98.29932
2000	98.57143
2001	98.83624
2002	99.09539
2003	99.34906
2004	99.51691
2005	99.76096
2006	100
2007	100.15613
2008	100.3867
2009	100.53599
2010	100.75873
2011	100.90158
2012	101.1169
2013	101.25461
2014	101.46306
2015	101.59536