Year	Percent
1991	19.183
1992	18.014
1993	20.4
1994	21.09
1995	18.384
1996	19.204
1997	19.527
1998	27.544
1999	22.916
2000	21.251
2001	20.785
2002	19.409
2003	19.733
2004	18.961
2005	18.678
2006	21.209
2007	21.106
2008	21.468
2009	20.538
2010	19.432
2011	17.912
2012	17.82
2013	17.412
2014	16.288
2015	15.824
2016	14.03
2017	14.157
2018	13.894
2019	13.667
2020	13.503
2021	13.384
2022	13.308