Year	Percent
1991	44.91257
1992	45.27713
1993	45.69509
1994	45.09348
1995	43.41733
1996	42.83837
1997	39.51042
1998	37.89498
1999	38.83776
2000	37.10221
2001	37.03012
2002	37.00132
2003	36.42185
2004	35.96955
2005	35.3927
2006	34.81235
2007	34.22266
2008	34.0323
2009	33.75947
2010	32.92304
2011	32.67626
2012	32.1614
2013	31.04963
2014	30.42013
2015	29.18917
2016	26.88433
2017	25.4398
2018	24.2932
2019	22.7786