Year	Percent
1991	51.624
1992	51.404
1993	51.412
1994	51.496
1995	51.361
1996	49.608
1997	48.151
1998	46.155
1999	45.008
2000	45.645
2001	45.309
2002	45.803
2003	45.884
2004	45.252
2005	45.228
2006	45.617
2007	45.739
2008	45.718
2009	44.885
2010	45.089
2011	45.007
2012	44.415
2013	45.347
2014	43.481
2015	43.515
2016	43.457
2017	43.201
2018	43.115
2019	42.983
2020	42.808
2021	42.555
2022	42.272