Year	Percent
1991	27.378
1992	27.261
1993	27.19
1994	27.257
1995	26.713
1996	26.165
1997	25.579
1998	25.07
1999	24.575
2000	24.038
2001	24.24
2002	24.421
2003	24.676
2004	24.878
2005	25.077
2006	23.301
2007	21.627
2008	19.977
2009	18.546
2010	17.153
2011	16.314
2012	15.495
2013	15.323
2014	15.042
2015	14.625
2016	14.174
2017	13.945
2018	13.714
2019	13.487
2020	13.261
2021	13.037
2022	12.811