Year	Percent
1991	19.967
1992	19.559
1993	19.22
1994	18.712
1995	18.592
1996	18.328
1997	18.052
1998	16.468
1999	16.102
2000	16.115
2001	14.991
2002	14.223
2003	14.119
2004	11.46
2005	11.322
2006	11.009
2007	10.827
2008	10.843
2009	11.591
2010	12.271
2011	12.155
2012	13.045
2013	13.861
2014	13.982
2015	13.284
2016	12.816
2017	12.586
2018	12.34
2019	12.115
2020	11.848
2021	11.571
2022	11.232