Year	Percent
1991	20.948
1992	10.421
1993	13.147
1994	15.266
1995	13.973
1996	14.639
1997	19.448
1998	17.383
1999	16.975
2000	14.906
2001	15.288
2002	13.749
2003	13.555
2004	13.541
2005	11.512
2006	11.697
2007	11.008
2008	10.281
2009	11.564
2010	11.534
2011	11.388
2012	11.417
2013	11.596
2014	11.587
2015	12.647
2016	12.912
2017	13.326
2018	13.328
2019	13.276
2020	13.235
2021	13.225
2022	13.211