Year	Percent
1991	15.629
1992	15.619
1993	14.566
1994	15.064
1995	14.951
1996	15.073
1997	14.464
1998	14.651
1999	15.386
2000	13.39
2001	14.403
2002	12.252
2003	11.641
2004	12.01
2005	12.406
2006	11.629
2007	12.643
2008	12.243
2009	10.049
2010	9.222
2011	9.347
2012	9.478
2013	9.183
2014	9.291
2015	9.665
2016	9.303
2017	9.492
2018	9.346
2019	9.21
2020	9.091
2021	8.963
2022	8.86