Year	Percent
1991	40.925
1992	41.802
1993	42.648
1994	43.792
1995	44.377
1996	45.36
1997	46.148
1998	47.311
1999	48.161
2000	48.887
2001	48.992
2002	49.517
2003	50.084
2004	50.203
2005	49.913
2006	49.77
2007	49.562
2008	49.494
2009	50.104
2010	50.019
2011	49.532
2012	49.439
2013	49.485
2014	49.339
2015	49.306
2016	49.392
2017	49.797
2018	50.096
2019	50.451
2020	50.823
2021	51.124
2022	51.401