Year	Percent
1991	59.7
1992	58.49999
1993	56.4
1994	54.3
1995	52.2
1996	50.5
1997	49.9
1998	49.8
1999	50.1
2000	50.01
2001	50.00999
2002	50.01
2003	49.1
2004	46.9
2005	44.8
2006	42.6
2007	40.79999
2008	39.6
2009	38.1
2010	36.7
2011	34.80118
2012	33.60226
2013	31.40315
2014	29.50388
2015	28.59302
2016	27.7049
2017	26.98513
2018	26.07398
2019	25.33715