Year	Percent
1970	81.87251
1971	82.22656
1972	82.75862
1973	83.27068
1974	83.94834
1975	84.42029
1976	84.90231
1977	85.34031
1978	85.93482
1979	86.50927
1980	87.06468
1981	87.45928
1982	88.14103
1983	88.64353
1984	89.28571
1985	89.75535
1986	90.49774
1987	90.93611
1988	91.50805
1989	92.19653
1990	92.59259
1991	93.24895
1992	93.88889
1993	94.50549
1994	95.11533
1995	95.7047
1996	96.28154
1997	96.85039
1998	97.53247
1999	97.94872
2000	98.35443
2001	98.99875
2002	99.38272
2003	99.87805
2004	100.24067
2005	100.71259
2006	101.17233
2007	101.50463
2008	101.82648
2009	102.36753
2010	102.66963
2011	102.96378
2012	103.35861
2013	103.63248
2014	103.90295
2015	104.16233