Year	Percent
1991	47.731
1992	47.303
1993	46.249
1994	44.908
1995	43.382
1996	42.656
1997	42.545
1998	43.204
1999	44.257
2000	44.641
2001	44.268
2002	44.281
2003	44.345
2004	43.976
2005	43.643
2006	44.503
2007	45.879
2008	47.244
2009	49.214
2010	51.269
2011	53.949
2012	55.258
2013	56.253
2014	56.909
2015	56.957
2016	57.339
2017	58.003
2018	58.92
2019	59.747
2020	60.176
2021	57.885
2022	55.687