Year	Percent
1991	17.993
1992	20.884
1993	21.26
1994	20.94
1995	19.606
1996	18.9
1997	16.805
1998	16.252
1999	16.121
2000	13.924
2001	15.782
2002	15.831
2003	16.284
2004	16.022
2005	16.002
2006	13.672
2007	11.399
2008	11.881
2009	12.62
2010	13.217
2011	13.937
2012	12.321
2013	11.556
2014	10.823
2015	10.769
2016	9.35
2017	9.301
2018	9.089
2019	8.892
2020	8.679
2021	8.469
2022	8.275