Year	%
1972	68.51253
1973	67.00668
1981	68.93122
1982	70.26016
1983	72.17317
1984	71.51372
1985	70.48549
1986	73.2429
1987	73.73535
1991	78.4624
1992	79.64384
1993	79.43421
1996	81.31214
1998	83.21658
1999	82.95452
2000	83.81976
2001	84.85627
2003	86.73195
2004	87.2133
2005	88.68637
2006	87.03986
2007	87.79125
2008	87.80158
2009	88.37221
2010	88.82498
2011	88.99818
2012	88.80592
2013	89.9367
2014	89.32742
2015	89.34994
2016	88.82797
2017	88.66323