Year	Percent
1991	16.962
1992	16.884
1993	16.806
1994	16.682
1995	16.469
1996	16.285
1997	16.036
1998	15.791
1999	15.519
2000	15.246
2001	15.026
2002	14.8
2003	14.582
2004	14.381
2005	14.172
2006	14.041
2007	13.911
2008	13.785
2009	13.658
2010	13.531
2011	13.437
2012	13.33
2013	13.216
2014	13.098
2015	12.971
2016	12.858
2017	12.705
2018	12.552
2019	12.399
2020	12.246
2021	12.094
2022	11.942