Year	Percent
1991	12.854
1992	12.826
1993	14.464
1994	16.311
1995	15.975
1996	15.899
1997	16.281
1998	13.948
1999	13.978
2000	14.978
2001	16.122
2002	15.766
2003	15.152
2004	14.203
2005	15.887
2006	15.356
2007	15.032
2008	14.585
2009	14.42
2010	14.953
2011	15.06
2012	15.77
2013	15.731
2014	15.42
2015	15.749
2016	15.994
2017	15.862
2018	15.532
2019	14.691
2020	14.472
2021	14.153
2022	13.959