Year	Percent
1991	52.40775
1992	52.10083
1993	52.03329
1994	51.32225
1995	51.09713
1996	50.67647
1997	50.8661
1998	50.12831
1999	50.05507
2000	51.20734
2001	49.96253
2002	51.86278
2003	52.32366
2004	51.49766
2005	49.41441
2006	48.2374
2007	47.65687
2008	45.9618
2009	46.13075
2010	45.54702
2011	43.51045
2012	42.47466
2013	41.62826
2014	40.97165
2015	40.08987
2016	39.48363
2017	38.75451
2018	37.91011
2019	37.26189