Year	Percent
1990	0.66366
1991	0.97645
1992	1.16991
1993	1.3453
1994	1.2101
1995	1.03761
1996	1.09046
1997	0.9307
1998	0.74798
1999	0.58084
2000	0.49728
2001	0.44263
2002	0.53232
2003	0.50688
2004	0.49033
2005	0.45954
2006	0.42499
2007	0.34087
2008	0.33237
2009	0.52548
2010	0.71272
2011	0.69287
2012	0.64182
2013	0.66146
2014	0.62839
2015	0.57349
2016	0.55739
2017	0.53653