Year	Percent
1991	52.9
1992	51.864
1993	51.36
1994	50.94
1995	50.513
1996	49.638
1997	49.022
1998	48.74
1999	48.096
2000	47.444
2001	46.404
2002	46.016
2003	45.538
2004	44.775
2005	44.207
2006	43.743
2007	43.672
2008	43.219
2009	43.464
2010	43.004
2011	42.461
2012	42.364
2013	41.875
2014	40.709
2015	39.743
2016	39.551
2017	39.828
2018	39.021
2019	38.201
2020	37.458
2021	36.761
2022	36.169