Year	Percent
1991	23.017
1992	24.053
1993	24.587
1994	24.918
1995	20.372
1996	21.562
1997	20.829
1998	19.782
1999	17.593
2000	17.745
2001	16.729
2002	16.49
2003	16.526
2004	16.337
2005	16.557
2006	17.003
2007	16.649
2008	16.745
2009	18.02
2010	17.592
2011	17.668
2012	18.042
2013	17.854
2014	18.465
2015	18.771
2016	18.395
2017	18.426
2018	18.306
2019	18.203
2020	18.122
2021	18.045
2022	17.973