Year	Percent
1991	26.132
1992	26.053
1993	25.88
1994	25.587
1995	25.203
1996	24.592
1997	23.613
1998	23.119
1999	22.569
2000	22.01
2001	21.676
2002	21.297
2003	20.976
2004	20.741
2005	20.519
2006	20.224
2007	16.084
2008	15.931
2009	15.725
2010	15.593
2011	15.494
2012	15.311
2013	15.125
2014	15.017
2015	14.948
2016	14.662
2017	14.348
2018	14.044
2019	13.703
2020	13.37
2021	13.041
2022	12.721