Year	Percent
1991	50.62
1992	51.108
1993	51.489
1994	51.783
1995	52.019
1996	52.585
1997	52.982
1998	53.253
1999	53.44
2000	53.569
2001	53.961
2002	54.205
2003	54.312
2004	54.277
2005	54.09
2006	54.157
2007	54.036
2008	53.755
2009	53.356
2010	52.874
2011	52.607
2012	52.215
2013	51.721
2014	51.132
2015	50.451
2016	49.95
2017	49.917
2018	49.848
2019	49.771
2020	49.695
2021	49.612
2022	49.531