Year	Percent
1991	54.117
1992	53.512
1993	53.541
1994	53.002
1995	51.78
1996	48.514
1997	47.572
1998	46.048
1999	45.95
2000	45.03
2001	44.941
2002	44.567
2003	44.161
2004	43.695
2005	43.621
2006	43.508
2007	42.666
2008	42.826
2009	41.845
2010	40.494
2011	40.245
2012	39.352
2013	37.926
2014	37.201
2015	35.833
2016	33.295
2017	32.173
2018	31.479
2019	30.766
2020	29.979
2021	29.171
2022	28.616