Year	Percent
1991	50.5
1992	50.172
1993	49.872
1994	49.676
1995	49.57
1996	49.613
1997	50.133
1998	50.329
1999	50.484
2000	50.709
2001	50.758
2002	50.806
2003	50.607
2004	50.65
2005	50.749
2006	50.856
2007	50.98
2008	51.354
2009	51.713
2010	52.328
2011	52.436
2012	52.539
2013	52.648
2014	52.683
2015	52.719
2016	52.707
2017	52.665
2018	52.634
2019	52.619
2020	52.624
2021	52.644
2022	52.683