Year	Percent
1990	0.38308
1991	0.59057
1992	0.99572
1993	0.89123
1994	0.87459
1995	0.66167
1996	0.63313
1997	0.52589
1998	0.42783
1999	0.35491
2000	0.31646
2001	0.39367
2002	0.73116
2003	0.91432
2004	0.81157
2005	0.6681
2006	0.56778
2007	0.5604
2008	0.8013
2009	2.01751
2010	2.73301
2011	2.38751
2012	1.97801
2013	1.68125
2014	1.25382
2015	0.94635
2016	0.79977
2017	0.6638