Year	%
1973	70.95701
1974	72.88952
1975	76.32126
1976	74.13079
1977	76.33952
1978	70.55347
1979	75.7285
1980	77.1546
1981	78.06977
1982	80.04171
1983	80.71027
1984	79.50418
1985	81.73778
1986	80.82558
1987	81.59901
1988	82.26492
1989	83.54622
1990	83.00611
1991	85.7354
1992	86.62228
1993	87.29258
1994	87.5265
1995	87.78688
1996	88.42379
1997	88.73068
1998	89.04007
1999	90.09615
2000	90.26549
2001	90.88826
2002	92.12183
2003	93.18232
2004	89.19545
2005	87.86541
2006	90.62632
2007	91.00908
2008	90.76591
2009	90.14649
2010	89.72764
2011	88.97635
2012	85.25821
2013	86.00381
2014	86.8764
2015	88.32392
2016	90.13361
2017	90.69714