Year	%
1986	75.43759
1987	76.39565
1988	74.93345
1989	75.7809
1990	77.90477
1991	79.51231
1992	81.45863
1993	81.29612
1994	82.91751
1995	85.48011
1996	86.14232
1997	86.08261
1998	86.2133
1999	86.91801
2000	87.07157
2001	88.5067
2002	87.95069
2003	89.02908
2004	89.11618
2005	89.89279
2006	90.91593
2007	90.86244
2008	90.86508
2010	90.37742
2011	90.94319
2012	89.90751
2013	89.65151
2014	89.87342
2015	90.51151
2016	90.25957
2017	90.73123