Year	%
1973	74.02748
1974	75.78304
1975	78.99763
1976	76.50464
1977	78.72173
1978	72.48135
1979	77.92076
1980	79.22658
1981	80.22055
1982	82.30568
1983	82.91957
1984	81.3281
1985	83.56403
1986	83.43743
1987	83.54155
1988	83.67264
1989	85.28472
1990	84.14482
1991	86.72363
1992	87.13736
1993	87.69872
1994	87.91414
1995	88.05263
1996	88.70915
1997	88.91977
1998	89.12982
1999	90.27082
2000	90.39522
2001	91.00464
2002	91.39523
2003	91.55947
2004	91.0134
2005	90.15964
2006	90.18017
2007	90.02836
2008	89.86345
2009	89.77063
2010	89.4412
2011	88.97717
2012	85.66523
2013	85.73451
2014	87.34003
2015	87.86988
2016	89.40095
2017	90.05728