Year	%
1988	73.91949
1989	74.77231
1990	78.39502
1991	80.48034
1992	83.59572
1993	82.86629
1994	85.26151
1995	89.79825
1996	90.28856
1997	89.61237
1998	88.75974
1999	89.76232
2000	90.68336
2001	91.69388
2002	92.80387
2003	93.77773
2004	94.46948
2005	95.27129
2006	96.35297
2007	97.19476
2008	97.47821
2009	97.30814
2010	97.33576
2011	96.98517
2012	96.52093
2013	95.89345
2014	97.43453
2015	97.3584
2016	97.5528
2017	97.64104