Year	%
1970	61.79828
1971	68.6995
1990	87.25882
1992	89.5843
1993	88.53819
1994	89.32312
1995	89.69012
1996	89.98533
1997	90.5091
1998	91.75032
1999	92.33539
2000	92.60377
2001	93.61997
2002	93.37534
2003	93.04713
2004	93.05976
2005	93.24882
2006	93.63455
2007	93.57426
2008	93.97026
2009	93.72015
2010	93.70975
2011	93.55652
2012	93.78905
2013	93.97258
2014	93.9413
2015	93.93537
2016	93.92525
2017	94.05535