Year	Percent
1991	53.674
1992	53.931
1993	50.336
1994	45.527
1995	44.024
1996	43.443
1997	40.711
1998	44.327
1999	42.796
2000	44.433
2001	43.379
2002	43.747
2003	45.713
2004	42.591
2005	43.775
2006	42.609
2007	41.197
2008	40.957
2009	40.785
2010	39.591
2011	37.438
2012	36.344
2013	35.63
2014	34.847
2015	33.332
2016	32.92
2017	32.306
2018	31.382
2019	30.555
2020	29.645
2021	28.783
2022	27.976