Year	Percent
1991	23.46
1992	23.098
1993	23.126
1994	22.824
1995	22.696
1996	22.368
1997	21.901
1998	21.528
1999	21.057
2000	20.533
2001	20.444
2002	20.114
2003	19.878
2004	17.745
2005	17.382
2006	16.707
2007	16.48
2008	15.856
2009	14.829
2010	14.099
2011	14.228
2012	13.798
2013	13.694
2014	13.333
2015	13.23
2016	12.901
2017	13.136
2018	12.939
2019	12.777
2020	12.688
2021	12.571
2022	12.452