Year	%
1988	73.9284
1989	75.0038
1990	78.84949
1991	81.24658
1992	84.68295
1993	83.43334
1994	85.83874
1995	90.99933
1996	91.36005
1997	90.10271
1998	88.8899
1999	89.7396
2000	90.70584
2001	91.71723
2002	92.67433
2003	93.72025
2004	94.87655
2005	95.93494
2006	96.90208
2007	97.90989
2008	97.9629
2009	97.92564
2010	97.92843
2011	97.63243
2012	96.85522
2013	95.67174
2014	97.75204
2015	98.03575
2016	98.36139
2017	98.40732