Year	%
1974	74.71506
1975	77.78303
1976	75.67056
1977	77.80227
1978	72.45499
1979	77.26431
1980	78.65945
1981	79.57201
1982	81.43792
1983	82.09022
1984	80.9066
1985	82.89705
1986	82.01411
1987	82.63783
1988	83.3397
1989	84.53367
1990	84.082
1991	86.62272
1992	87.49455
1993	88.17077
1994	88.44901
1995	88.68066
1996	89.27952
1997	89.55283
1998	89.83321
1999	90.82578
2000	91.02749
2001	91.6053
2002	92.72647
2003	93.67007
2004	90.11442
2005	88.96623
2006	91.46217
2007	91.83379
2008	91.68762
2009	91.21134
2010	90.90289
2011	90.31392
2012	87.06468
2013	87.17185
2014	88.62572
2015	89.31213
2016	90.33114
2017	90.91456