Year	Percent
1991	12.688
1992	12.811
1993	12.724
1994	12.724
1995	12.649
1996	12.697
1997	12.574
1998	12.5
1999	12.456
2000	12.423
2001	12.644
2002	12.776
2003	13.405
2004	13.581
2005	13.921
2006	13.512
2007	13.263
2008	12.922
2009	12.94
2010	12.885
2011	13.302
2012	13.981
2013	14.659
2014	15.422
2015	16.202
2016	16.892
2017	16.999
2018	17.099
2019	17.189
2020	17.273
2021	17.349
2022	17.419