Year	Percent
1991	49.736
1992	49.696
1993	49.488
1994	49.23
1995	49.004
1996	49.902
1997	50.844
1998	51.738
1999	52.744
2000	53.738
2001	55.149
2002	55.277
2003	55.325
2004	55.351
2005	55.311
2006	56.26
2007	57.854
2008	58.152
2009	58.393
2010	58.565
2011	58.83
2012	58.948
2013	59.006
2014	59.012
2015	58.975
2016	59.025
2017	59.218
2018	59.413
2019	59.607
2020	59.801
2021	59.995
2022	60.188