Year	Percent
1991	35.292
1992	35.996
1993	36.43
1994	36.56
1995	36.334
1996	34.663
1997	34.788
1998	34.401
1999	34.415
2000	34.408
2001	34.098
2002	32.08
2003	31.371
2004	29.8
2005	30.26
2006	30.12
2007	30.269
2008	30.414
2009	30.23
2010	28.494
2011	29.262
2012	26.865
2013	30.094
2014	28.35
2015	26.836
2016	23.963
2017	23.759
2018	23.536
2019	23.267
2020	22.89
2021	22.431
2022	21.901