Year	Percent
1967-01-01	1.87500000000000
1968-01-01	1.85000000000000
1969-01-01	1.80000000000000
1970-01-01	1.62500000000000
1971-01-01	1.92500000000000
1972-01-01	2.62500000000000
1973-01-01	2.32500000000000
1974-01-01	2.70000000000000
1975-01-01	4.92500000000000
1976-01-01	4.75000000000000
1977-01-01	5.65000000000000
1978-01-01	6.44253313333333
1979-01-01	6.26549923333333
1980-01-01	6.10624537500000
1981-01-01	5.78357090000000
1982-01-01	7.15613189166667
1983-01-01	9.96159320833333
1984-01-01	8.98968037500000
1985-01-01	8.26298630833334
1986-01-01	8.08103871666667
1987-01-01	8.10803962500000
1988-01-01	7.22795430000000
1989-01-01	6.17982545833333
1990-01-01	6.92300003333333
1991-01-01	9.57652190833333
1992-01-01	10.72813549166670
1993-01-01	10.87466526666670
1994-01-01	9.72219025833333
1995-01-01	8.47228147500000
1996-01-01	8.50611403333334
1997-01-01	8.36248737500000
1998-01-01	7.67742941666667
1999-01-01	6.87379136666667
2000-01-01	6.28554620833333
2001-01-01	6.74217304166667
2002-01-01	6.36891133333333
2003-01-01	5.92842029166667
2004-01-01	5.39673355000000
2005-01-01	5.03388074166667
2006-01-01	4.78523972500000
2007-01-01	4.37915150833333
2008-01-01	4.23432970833333
2009-01-01	5.56038543333333
2010-01-01	5.21334044166667
2011-01-01	5.08135500000000
2012-01-01	5.22434862500000
2013-01-01	5.66305586666667
2014-01-01	6.07883751666667
2015-01-01	6.05794608333333
2016-01-01	5.71112978333333
2017-01-01	5.59642559166667