Year	Percent
1990	0.65427
1991	0.62854
1992	0.60925
1993	0.59155
1994	0.45987
1995	0.72015
1996	0.70007
1997	0.68908
1998	0.67971
1999	0.66596
2000	0.65548
2001	0.58344
2002	0.64298
2003	0.40402
2004	0.35682
2005	0.4175
2007	0.59392
2008	0.58378
2009	0.58288
2010	0.57304
2011	0.35892
2012	0.35278
2013	0.34694
2014	0.34118
2015	0.33532
2016	0.32955
2017	0.34253
2018	0.32917
2019	0.33135
2020	0.32467