Year	Percent
1991	55.977
1992	56.439
1993	56.069
1994	56.079
1995	55.603
1996	55.817
1997	55.804
1998	56.334
1999	56.397
2000	56.4
2001	56.318
2002	56.031
2003	56.053
2004	55.483
2005	55.232
2006	55.131
2007	54.897
2008	54.809
2009	54.63
2010	54.194
2011	54.933
2012	55.383
2013	51.701
2014	52.818
2015	52.75
2016	52.941
2017	52.582
2018	52.386
2019	52.144
2020	51.84
2021	51.484
2022	51.626