Year	Percent
1991	27.187
1992	25.955
1993	25.082
1994	23.925
1995	25.493
1996	25.649
1997	24.212
1998	23.832
1999	23.185
2000	22.513
2001	21.798
2002	21.361
2003	21.131
2004	20.607
2005	20.064
2006	19.734
2007	18.797
2008	17.653
2009	17.928
2010	17.064
2011	16.801
2012	17.57
2013	15.956
2014	15.539
2015	13.797
2016	14.19
2017	14.192
2018	14.009
2019	13.757
2020	13.466
2021	13.122
2022	12.765