Year	Percent
1990	0.38946
1991	0.3822
1992	0.36521
1993	0.36317
1994	0.34813
1995	0.37455
1996	0.36592
1997	0.36298
1998	0.37354
1999	0.37421
2000	0.36672
2001	0.37279
2002	0.37584
2003	0.37719
2004	0.377
2005	0.408
2006	0.37735
2007	0.36178
2008	0.36267
2009	0.39181
2010	0.39314
2011	0.39519
2012	0.39653
2013	0.39502
2014	0.39379
2015	0.39327
2016	0.39132
2017	0.38825
2018	0.38187
2019	0.37801
2020	0.37851