Year	Percent
1991	49.397
1992	49.217
1993	48.9
1994	48.475
1995	47.958
1996	47.943
1997	47.834
1998	47.625
1999	47.317
2000	46.917
2001	47.178
2002	47.269
2003	47.234
2004	47.127
2005	46.968
2006	47.366
2007	47.657
2008	47.831
2009	47.865
2010	47.738
2011	48.535
2012	49.206
2013	49.721
2014	50.095
2015	50.357
2016	50.111
2017	50.578
2018	51.036
2019	51.479
2020	51.906
2021	52.342
2022	52.764