Year	Percent
1991	18.83467
1992	17.43322
1993	15.35184
1994	14.19263
1995	12.95768
1996	11.87501
1997	12.00967
1998	12.46003
1999	12.44602
2000	11.5503
2001	9.89254
2002	9.29521
2003	9.60994
2004	8.46561
2005	11.03208
2006	14.18226
2007	13.85922
2008	11.86457
2009	7.35477
2010	4.82868
2011	4.17636
2012	4.04982
2013	3.71991
2014	5.00373
2015	7.67366
2016	6.58882