Year	Percent
1991	15.788
1992	15.108
1993	14.436
1994	13.95
1995	14.743
1996	13.969
1997	13.894
1998	15.078
1999	14.194
2000	14.237
2001	13.761
2002	13.641
2003	12.875
2004	12.353
2005	12.287
2006	11.853
2007	11.46
2008	10.397
2009	9.963
2010	9.904
2011	9.294
2012	9.053
2013	9.068
2014	8.619
2015	8.737
2016	8.809
2017	8.94
2018	8.746
2019	8.549
2020	8.41
2021	8.294
2022	8.206