Year	%
1986	76.05912
1987	76.94887
1988	75.38813
1989	76.24898
1990	78.52797
1991	80.31262
1992	82.39046
1993	82.29363
1994	83.96484
1995	86.69216
1996	87.26856
1997	87.21504
1998	87.13806
1999	87.96875
2000	88.07592
2001	89.60207
2002	89.00749
2003	90.14762
2004	90.04293
2005	90.92013
2006	91.9429
2007	91.82518
2008	92.24424
2009	91.92282
2010	91.64438
2011	92.20343
2012	91.40279
2014	91.47963
2016	91.93122
2017	92.53497