Year	Percent
1991	56.011
1992	57.53
1993	55.844
1994	56.232
1995	55.739
1996	55.064
1997	54.535
1998	54.159
1999	54.331
2000	53.328
2001	52.661
2002	52.955
2003	52.546
2004	52.496
2005	52.202
2006	51.639
2007	51.326
2008	51.291
2009	51.549
2010	50.369
2011	50.978
2012	51.202
2013	49.098
2014	48.737
2015	48.49
2016	48.16
2017	48.245
2018	48.144
2019	48.042
2020	47.94
2021	47.84
2022	47.74