Year	Percent
1991	54.672
1992	54.585
1993	54.919
1994	55.259
1995	55.592
1996	55.924
1997	56.251
1998	56.579
1999	56.902
2000	57.224
2001	57.544
2002	57.847
2003	55.972
2004	54.109
2005	52.275
2006	50.461
2007	48.684
2008	46.964
2009	45.313
2010	43.826
2011	44.37
2012	44.197
2013	43.985
2014	43.756
2015	43.513
2016	43.336
2017	43.068
2018	42.794
2019	42.513
2020	42.222
2021	41.923
2022	41.616