Year	Percent
1991	56.202
1992	55.767
1993	55.186
1994	54.895
1995	54.585
1996	54.256
1997	54.136
1998	54.98
1999	54.168
2000	54.264
2001	55.19
2002	58.166
2003	56.615
2004	56.914
2005	54.595
2006	53.993
2007	51.028
2008	48.75
2009	50.159
2010	46.389
2011	45.812
2012	45.662
2013	44.569
2014	42.937
2015	43.405
2016	43.615
2017	43.755
2018	43.562
2019	43.333
2020	43.115
2021	42.909
2022	42.721