Year	Percent
1991	53.048
1992	49.067
1993	48.201
1994	47.151
1995	47.377
1996	47.13
1997	45.478
1998	43.917
1999	43.203
2000	43.717
2001	43.491
2002	43.669
2003	46.686
2004	43.214
2005	42.979
2006	42.362
2007	42.277
2008	41.719
2009	41.426
2010	41.065
2011	40.704
2012	39.917
2013	39.707
2014	39.791
2015	39.215
2016	38.424
2017	38.167
2018	38.09
2019	38.009
2020	37.92
2021	37.826
2022	37.731