Year	Percent
1991	76.84779
1992	77.05221
1993	76.80499
1994	76.7571
1995	76.60988
1996	76.28158
1997	76.24014
1998	76.46035
1999	76.3554
2000	76.7029
2001	76.91955
2002	77.40836
2003	78.01264
2004	77.92077
2005	78.12083
2006	77.43133
2007	76.64926
2008	75.83467
2009	75.03754
2010	74.03411
2011	73.04381
2012	72.10688
2013	71.0336
2014	70.21259
2015	69.40647
2016	68.64453
2017	67.90484
2018	67.3011
2019	66.6231