Year	Percent
1991	13.455
1992	13.065
1993	13.237
1994	12.696
1995	12.297
1996	12.752
1997	12.495
1998	12.415
1999	12.53
2000	12.029
2001	11.676
2002	11.738
2003	12.161
2004	11.767
2005	12.059
2006	12.203
2007	11.777
2008	11.908
2009	12.293
2010	12.265
2011	12.204
2012	11.976
2013	11.744
2014	11.811
2015	12.07
2016	15.89
2017	15.862
2018	15.852
2019	15.84
2020	15.826
2021	15.813
2022	15.8