Year	Percent
1990	0.1778
1991	0.28613
1992	0.53195
1993	0.49908
1994	0.59187
1995	0.48339
1996	0.47714
1997	0.41218
1998	0.3272
1999	0.29141
2000	0.25369
2001	0.31028
2002	0.55889
2003	0.64812
2004	0.60455
2005	0.51893
2006	0.42948
2007	0.42834
2008	0.57804
2009	1.3347
2010	1.81506
2011	1.81229
2012	1.61015
2013	1.322
2014	1.00901
2015	0.7134
2016	0.61256
2017	0.54742