Year	Percent
1991	57.251
1992	57.297
1993	57.212
1994	56.966
1995	56.395
1996	56.103
1997	55.989
1998	55.766
1999	55.48
2000	55.159
2001	55.053
2002	55.781
2003	56.472
2004	57.093
2005	57.831
2006	58.653
2007	59.38
2008	58.849
2009	58.313
2010	58.18
2011	57.776
2012	57.309
2013	56.763
2014	56.121
2015	55.719
2016	55.374
2017	55.131
2018	54.882
2019	54.652
2020	54.443
2021	54.254
2022	54.079