Year	Percent
1991	63.146
1992	59.7
1993	56.819
1994	54.613
1995	52.703
1996	50.515
1997	53.841
1998	51.42
1999	53.362
2000	55.276
2001	57.142
2002	55.123
2003	55.097
2004	55.026
2005	54.777
2006	57.274
2007	58.604
2008	60.092
2009	59.766
2010	59.791
2011	57.282
2012	55.085
2013	54.621
2014	54.34
2015	54.894
2016	55.479
2017	54.941
2018	55.343
2019	55.671
2020	56.037
2021	56.394
2022	56.766