Year	Percent
1990	0.67422
1991	0.64206
1992	0.63916
1993	0.63253
1994	0.56028
1995	0.55214
1996	0.52394
1997	0.50112
1998	0.49968
1999	0.49494
2000	0.47343
2001	0.46561
2002	0.42679
2003	0.41357
2004	0.37433
2005	0.41002
2006	0.40073
2007	0.39511
2008	0.39189
2009	0.4188
2010	0.41545
2011	0.36262
2012	0.36155
2013	0.35495
2014	0.34345
2015	0.35301
2016	0.34049
2017	0.32846
2018	0.33633
2019	0.3175
2020	0.34559