Year	Percent
1991	59.959
1992	59.166
1993	57.723
1994	56.461
1995	56.815
1996	56.748
1997	56.194
1998	56.416
1999	56.528
2000	57.525
2001	58.175
2002	57.905
2003	58.058
2004	57.715
2005	57.662
2006	57.357
2007	57.595
2008	57.919
2009	56.732
2010	56.575
2011	56.291
2012	55.88
2013	55.269
2014	54.527
2015	54.153
2016	54.239
2017	54.437
2018	54.528
2019	54.402
2020	54.291
2021	54.162
2022	54.042