Year	Percent
1991	75.57
1992	74.03
1993	72.916
1994	71.964
1995	71.123
1996	70.409
1997	66.015
1998	65.594
1999	65.447
2000	66.288
2001	64.976
2002	63.141
2003	61.711
2004	59.989
2005	56.732
2006	53.787
2007	52.841
2008	52.864
2009	51.917
2010	51.103
2011	50.643
2012	49.908
2013	48.782
2014	48.126
2015	45.606
2016	43.486
2017	42.369
2018	40.978
2019	39.677
2020	38.409
2021	37.189
2022	36.158