Year	Percent
1991	37.622
1992	38.079
1993	40.027
1994	41.625
1995	40.579
1996	39.053
1997	39.717
1998	42.689
1999	43.648
2000	43.734
2001	42.829
2002	43.507
2003	44.951
2004	43.264
2005	43.325
2006	44.419
2007	44.786
2008	44.894
2009	44.317
2010	44.472
2011	45.135
2012	45.511
2013	46.602
2014	46.17
2015	45.507
2016	44.873
2017	45.18
2018	45.503
2019	45.821
2020	46.122
2021	46.422
2022	46.706