Year	Percent
1991	12.721
1992	12.414
1993	12.211
1994	11.682
1995	12.447
1996	12.571
1997	12.493
1998	14.032
1999	13.987
2000	13.851
2001	13.871
2002	14.592
2003	14.126
2004	14.522
2005	14.364
2006	15.75
2007	16.229
2008	15.273
2009	15.344
2010	15.665
2011	15.372
2012	16.33
2013	15.948
2014	17.226
2015	17.221
2016	17.305
2017	17.372
2018	17.401
2019	17.409
2020	17.405
2021	17.397
2022	17.386