Year	Percent
1991	46.254
1992	45.783
1993	44.875
1994	44.033
1995	43.602
1996	43.505
1997	42.943
1998	43.307
1999	42.249
2000	40.493
2001	39.967
2002	38.708
2003	38.606
2004	38.094
2005	38.638
2006	39.731
2007	41.633
2008	43.075
2009	43.314
2010	43.432
2011	43.345
2012	43.445
2013	43.359
2014	44.45
2015	45.219
2016	45.968
2017	46.388
2018	46.402
2019	46.13
2020	45.953
2021	45.747
2022	45.529