Year	Measure
1990	0.849
1991	0.853
1992	0.855
1993	0.854
1994	0.858
1995	0.86
1996	0.863
1997	0.862
1998	0.861
1999	0.864
2000	0.867
2001	0.872
2002	0.877
2003	0.881
2004	0.886
2005	0.891
2006	0.894
2007	0.897
2008	0.898
2009	0.898
2010	0.903
2011	0.907
2012	0.909
2013	0.912
2014	0.919
2015	0.92