Year	Percent
1991	6.485
1992	6.361
1993	6.556
1994	6.696
1995	6.829
1996	7.434
1997	7.797
1998	8.274
1999	8.749
2000	8.947
2001	9.363
2002	9.715
2003	9.609
2004	9.81
2005	10.249
2006	10.467
2007	10.818
2008	11.043
2009	11.253
2010	11.704
2011	12.42
2012	13.36
2013	13.851
2014	14.448
2015	14.687
2016	14.797
2017	14.85
2018	15.157
2019	15.353
2020	15.664
2021	16.022
2022	16.633