Year	Percent
1991	55.046
1992	53.85
1993	52.229
1994	51.955
1995	52.766
1996	52.123
1997	53.031
1998	53.708
1999	53.872
2000	54.548
2001	55.006
2002	55.469
2003	55.664
2004	55.85
2005	55.528
2006	55.681
2007	55.173
2008	54.889
2009	54.47
2010	53.899
2011	52.111
2012	51.366
2013	50.947
2014	50.141
2015	49.642
2016	49.588
2017	49.421
2018	49.268
2019	49.104
2020	48.932
2021	48.753
2022	48.561