Year	Percent
1991	21.96388
1992	21.59045
1993	21.28383
1994	20.8101
1995	20.4271
1996	20.2766
1997	19.8418
1998	17.88891
1999	17.42981
2000	17.39561
2001	15.86792
2002	15.22598
2003	15.0325
2004	12.3713
2005	12.15892
2006	11.72442
2007	11.32968
2008	11.14431
2009	11.69601
2010	12.39641
2011	12.34921
2012	13.00408
2013	13.6927
2014	13.5705
2015	12.8979
2016	12.37273
2017	12.08098
2018	12.26769
2019	11.59906