Year	Percent
1991	15.446
1992	14.894
1993	14.532
1994	14.639
1995	14.277
1996	14.46
1997	13.88
1998	13.827
1999	13.705
2000	13.546
2001	13.455
2002	13.544
2003	13.072
2004	12.594
2005	12.99
2006	13.084
2007	13.722
2008	13.578
2009	13.676
2010	13.851
2011	13.316
2012	13.113
2013	13.241
2014	13.329
2015	13.033
2016	12.75
2017	12.678
2018	12.555
2019	12.464
2020	12.408
2021	12.358
2022	12.314