Year	Percent
1991	12.529
1992	13.651
1993	13.894
1994	15.028
1995	14.54
1996	13.58
1997	13.2
1998	13.429
1999	13.385
2000	13.205
2001	12.898
2002	12.927
2003	14.743
2004	17.316
2005	17.676
2006	17.233
2007	18.509
2008	18.124
2009	17.549
2010	16.956
2011	17.523
2012	17.546
2013	18.075
2014	18.122
2015	17.798
2016	17.404
2017	17.714
2018	17.598
2019	17.487
2020	17.158
2021	16.809
2022	16.443