Year	Percent
1991	58.694
1992	58.388
1993	57.995
1994	57.428
1995	56.648
1996	56.343
1997	55.798
1998	55.082
1999	54.314
2000	53.569
2001	53.046
2002	52.512
2003	51.287
2004	50.078
2005	48.901
2006	48
2007	48.011
2008	47.994
2009	47.958
2010	47.912
2011	47.831
2012	48.198
2013	48.539
2014	48.828
2015	49.133
2016	48.944
2017	48.704
2018	48.458
2019	48.207
2020	48.135
2021	48.023
2022	47.888