Year	Percent
1990	0.80161
1991	0.79796
1992	0.79167
1993	0.7889
1994	0.74025
1995	0.63597
1996	0.64604
1997	0.63749
1998	0.63108
1999	0.60179
2000	0.54183
2001	0.53338
2002	0.51738
2003	0.53526
2004	0.51353
2005	0.5083
2006	0.47884
2007	0.50287
2008	0.48981
2009	0.49296
2010	0.48496
2011	0.48175
2012	0.46809
2013	0.46605
2014	0.46077
2015	0.46039
2016	0.4541
2017	0.44595
2018	0.43663
2019	0.43422
2020	0.4416