Year	%
1988	66.37466
1989	66.79863
1990	71.1187
1991	73.10676
1992	76.95318
1993	76.30172
1994	79.58038
1995	85.62214
1996	85.98083
1997	85.05599
1998	84.01551
1999	85.45135
2000	86.85977
2001	88.47901
2002	89.92703
2003	91.24013
2004	91.13815
2005	93.91868
2006	96.32601
2007	96.3347
2008	96.47068
2009	96.08493
2010	96.00988
2011	96.72552
2012	95.17352
2013	93.87795
2014	96.06411
2015	96.54251
2016	96.56695
2017	96.61981