Year	Measure
1990	0.272
1991	0.267
1992	0.262
1993	0.265
1994	0.268
1995	0.269
1996	0.275
1997	0.279
1998	0.286
1999	0.292
2000	0.302
2001	0.306
2002	0.322
2003	0.332
2004	0.341
2005	0.348
2006	0.357
2007	0.367
2008	0.375
2009	0.384
2010	0.392
2011	0.401
2012	0.413
2013	0.426
2014	0.431
2015	0.42