Year	Measure
1999	0.455
2000	0.442
2001	0.446
2002	0.453
2003	0.459
2004	0.465
2005	0.47
2006	0.482
2007	0.489
2008	0.494
2009	0.492
2010	0.497
2011	0.505
2012	0.509
2013	0.512
2014	0.514
2015	0.515