Year	Percent
1991	25.852
1992	24.451
1993	24.708
1994	24.579
1995	23.136
1996	23.81
1997	23.301
1998	22.681
1999	21.68
2000	21.769
2001	22.799
2002	22.639
2003	22.369
2004	21.708
2005	21.28
2006	20.67
2007	20.184
2008	19.098
2009	17.913
2010	17.816
2011	17.225
2012	17.2
2013	16.995
2014	16.632
2015	16.171
2016	16.105
2017	16.093
2018	15.958
2019	15.869
2020	15.727
2021	15.613
2022	15.526