Year	Percent
1991	62.614
1992	61.704
1993	59.259
1994	57.922
1995	57.229
1996	54.077
1997	54.083
1998	45.369
1999	43.872
2000	46.663
2001	41.23
2002	39.563
2003	38.996
2004	37.812
2005	37.276
2006	37.025
2007	36.269
2008	35.724
2009	35.954
2010	36.652
2011	35.803
2012	35.407
2013	35.962
2014	35.744
2015	36.201
2016	36.429
2017	36.127
2018	36.141
2019	36.144
2020	36.141
2021	36.123
2022	36.099