Year	Percent
1990	0.28887
1991	0.29196
1992	0.28397
1993	0.2759
1994	0.28293
1995	0.41454
1996	0.39579
1997	0.39322
1998	0.38237
1999	0.41859
2000	0.29025
2001	0.41332
2002	0.40326
2003	0.37133
2004	0.48293
2005	0.47471
2006	0.39666
2007	0.40477
2008	0.40071
2009	0.39629
2010	0.3902
2011	0.38358
2012	0.37665
2013	0.36959
2014	0.36278
2015	0.35631
2016	0.34979
2017	0.32904
2018	0.33026
2019	0.32314
2020	0.31999