Year	Percent
1990	0.38198
1991	0.40306
1992	0.29392
1993	0.25327
1994	0.2395
1995	0.37282
1996	0.36991
1997	0.43598
1998	0.484
1999	0.50331
2000	0.48965
2001	0.41616
2002	0.40339
2003	0.47075
2004	0.29908
2005	0.29431
2007	0.62222
2008	0.64496
2009	0.66728
2010	0.65483
2011	0.54171
2012	0.5316
2013	0.51407
2014	0.49701
2015	0.48094
2016	0.46462
2017	0.44831
2018	0.43548
2019	0.42203
2020	0.413