Year	%
1979	92.90362
1980	93.04283
1981	92.60581
1982	92.65254
1983	93.02224
1984	93.39696
1985	93.6817
1986	93.09293
1987	92.96967
1988	92.25069
1989	92.63091
1990	92.83063
1991	93.34628
1992	93.91777
1993	94.37853
1994	94.08213
1995	94.47966
1996	95.62455
1997	95.89508
1998	96.42606
1999	96.80526
2000	97.21677
2001	96.52758
2002	96.6228
2003	97.52781
2004	98.02064
2005	98.5094
2006	98.4586
2007	98.43353
2008	98.3612
2009	98.32565
2010	98.38581
2011	98.42549
2012	97.32627
2013	98.01712
2014	98.15837
2015	98.60205
2016	98.61243
2017	98.71565