Year	Percent
1991	18.064
1992	19.246
1993	18.278
1994	20.689
1995	21.276
1996	21.634
1997	21.635
1998	22.306
1999	22.02
2000	24.101
2001	23.379
2002	24.697
2003	22.198
2004	16.945
2005	19.6
2006	20.326
2007	17.284
2008	19.169
2009	18.996
2010	19.226
2011	18.778
2012	17.582
2013	20.28
2014	18.494
2015	17.501
2016	15.762
2017	15.578
2018	15.302
2019	15.045
2020	14.813
2021	14.565
2022	14.281