Year	%
1979	96.33546
1980	96.66454
1981	96.4392
1982	96.373
1983	96.79989
1984	97.1399
1985	97.47033
1986	97.3169
1987	97.20976
1988	97.16073
1989	97.03406
1990	96.79108
1991	97.00972
1992	97.34976
1993	97.13917
1994	96.96003
1995	97.32566
1996	97.36559
1997	97.51081
1998	97.65868
1999	97.7594
2000	97.78643
2001	97.74061
2002	97.65735
2003	97.59752
2004	97.67704
2005	97.61516
2006	97.52002
2007	97.70267
2008	97.67427
2009	97.64727
2010	97.64826
2011	97.66351
2012	97.64347
2013	97.70603
2014	97.277
2015	97.59958
2016	97.59606
2017	97.55323