Year	Number of Years
1978-01-01	63.4146341463415
1979-01-01	63.9548780487805
1980-01-01	63.4497560975610
1981-01-01	63.0748780487805
1982-01-01	63.1926829268293
1983-01-01	63.3000000000000
1984-01-01	63.4665853658537
1985-01-01	63.8336585365854
1986-01-01	64.2487804878049
1987-01-01	64.6541463414634
1988-01-01	64.5824390243903
1989-01-01	64.6675609756098
1990-01-01	65.0682926829268
1991-01-01	65.0317073170732
1992-01-01	65.1960975609756
1993-01-01	65.5853658536585
1994-01-01	65.9009756097561
1995-01-01	65.6441463414634
1996-01-01	65.7673170731707
1997-01-01	65.7980487804878
1998-01-01	66.1570731707317
1999-01-01	66.4034146341464
2000-01-01	66.9634146341463
2001-01-01	67.6078048780488
2002-01-01	68.1626829268293
2003-01-01	68.4353658536586
2004-01-01	68.8068292682927
2005-01-01	69.2207317073171
2006-01-01	69.5192682926829
2007-01-01	69.9826829268293
2008-01-01	70.2134146341463
2009-01-01	70.4678048780488
2010-01-01	70.8570731707317
2011-01-01	71.0624390243902
2012-01-01	71.2990243902439
2013-01-01	71.8304878048781