Year	Percent
1991	60.862
1992	60.15
1993	58.661
1994	58.905
1995	59.847
1996	59.825
1997	60.473
1998	61.151
1999	60.184
2000	59.59
2001	61.068
2002	61.089
2003	59.28
2004	61.83
2005	61.983
2006	62.461
2007	63.746
2008	62.993
2009	61.691
2010	60.631
2011	58.725
2012	57.964
2013	57.284
2014	57.558
2015	57.794
2016	56.81
2017	57.388
2018	57.071
2019	56.638
2020	56.131
2021	55.578
2022	54.996