Year	Percent
1991	82.13533
1992	82.71846
1993	83.93646
1994	83.76839
1995	84.2904
1996	81.29571
1997	82.39498
1998	78.94453
1999	77.31146
2000	81.33598
2001	82.5085
2002	85.52001
2003	85.58889
2004	83.06053
2005	82.89805
2006	78.55127
2007	83.24897
2008	85.4423
2009	89.7228
2010	94.37372
2011	96.4654
2012	95.9243
2013	95.92658
2014	93.28726
2015	90.6635
2016	92.51901