Year	Percent
1991	19.887
1992	15.908
1993	17.052
1994	18.399
1995	21.1
1996	22.544
1997	22.885
1998	22.176
1999	23.607
2000	22.788
2001	24.629
2002	23.691
2003	23.939
2004	21.885
2005	19.44
2006	19.079
2007	17.398
2008	14.406
2009	14.866
2010	13.208
2011	12.589
2012	13.324
2013	13.975
2014	14.057
2015	14.628
2016	15.309
2017	15.764
2018	15.76
2019	15.759
2020	15.737
2021	15.73
2022	15.724