Year	Percent
1991	58.727
1992	58.163
1993	57.83
1994	57.067
1995	56.1
1996	56.214
1997	55.975
1998	55.872
1999	54.893
2000	54.047
2001	54.589
2002	53.406
2003	52.766
2004	50.983
2005	49.918
2006	48.841
2007	48.004
2008	47.701
2009	47.148
2010	46.486
2011	44.27
2012	43.006
2013	42.567
2014	41.308
2015	40.059
2016	39.067
2017	38.346
2018	37.203
2019	36.094
2020	34.975
2021	33.963
2022	33.193