Year	Measure
1990	0.331
1991	0.337
1992	0.345
1993	0.352
1994	0.358
1995	0.365
1996	0.373
1997	0.382
1998	0.388
1999	0.394
2000	0.399
2001	0.403
2002	0.409
2003	0.415
2004	0.423
2005	0.43
2006	0.44
2007	0.444
2008	0.456
2009	0.461
2010	0.463
2011	0.468
2012	0.478
2013	0.485
2014	0.488
2015	0.49