Year	Percent
1991	0.6506
1992	0.64078
1993	0.63076
1994	0.61756
1995	0.60372
1996	0.58776
1997	0.57127
1998	0.55377
1999	0.53492
2000	0.51307
2001	0.48786
2002	0.46474
2003	0.44364
2004	0.41888
2005	0.39847
2006	0.38248
2007	0.36504
2008	0.34784
2009	0.33195
2010	0.31575
2011	0.30427
2012	0.29365
2013	0.28292
2014	0.27248
2015	0.26435
2016	0.25523
2017	0.24748
2018	0.23957
2019	0.23206