Year	Percent
1991	51.164
1992	50.815
1993	50.58
1994	50.183
1995	49.893
1996	49.821
1997	49.381
1998	48.823
1999	48.684
2000	48.746
2001	48.252
2002	48.428
2003	48.204
2004	47.639
2005	47.462
2006	47.096
2007	46.533
2008	46.5
2009	45.266
2010	45.111
2011	44.24
2012	43.763
2013	43.318
2014	42.961
2015	42.515
2016	41.935
2017	41.895
2018	41.813
2019	41.728
2020	41.642
2021	41.557
2022	41.472