Year	Percent
1991	17.493
1992	17.146
1993	17.286
1994	17.319
1995	18.614
1996	18.019
1997	18.974
1998	18.836
1999	18.988
2000	17.227
2001	18.188
2002	17.835
2003	17.162
2004	18.022
2005	18.016
2006	18.03
2007	18.152
2008	18.063
2009	18.467
2010	17.429
2011	16.847
2012	17.053
2013	16.459
2014	16.734
2015	17.071
2016	16.981
2017	16.136
2018	15.927
2019	15.992
2020	15.795
2021	15.914
2022	15.977