Year	Percent
1991	44.73
1992	44.831
1993	44.767
1994	44.612
1995	44.488
1996	44.544
1997	44.421
1998	44.196
1999	44.085
2000	44.086
2001	44.19
2002	44.244
2003	44.284
2004	47.303
2005	45.696
2006	44.101
2007	42.498
2008	40.938
2009	39.4
2010	37.876
2011	36.4
2012	34.92
2013	33.512
2014	32.242
2015	31.92
2016	31.559
2017	31.415
2018	31.267
2019	31.11
2020	30.908
2021	30.705
2022	30.488