Year	Percent
1991	16.125
1992	13.355
1993	12.939
1994	11.859
1995	9.061
1996	10.091
1997	15.002
1998	10.554
1999	11.707
2000	12.652
2001	11.924
2002	11.261
2003	10.364
2004	10.25
2005	10.288
2006	10.736
2007	11.061
2008	12.238
2009	10.963
2010	10.51
2011	11.214
2012	10.078
2013	9.297
2014	8.637
2015	8.157
2016	8.44
2017	8.469
2018	8.769
2019	8.589
2020	8.443
2021	8.417
2022	8.371