Year	Index
1979-01-01	48.7
1989-01-01	58.9
1991-01-01	58.2
1995-01-01	57.8
1997-01-01	58.2
1998-01-01	57.5
1999-01-01	56.5
2000-01-01	56.8
2001-01-01	56.9
2002-01-01	56.2
2003-01-01	55.8
2004-01-01	54.9
2005-01-01	53.9
2006-01-01	54.7
2007-01-01	52.8
2008-01-01	53.4
2009-01-01	51.9
2010-01-01	51.7
2011-01-01	51.4
2012-01-01	51.8
2013-01-01	51.5
2014-01-01	50.6
2015-01-01	50.8
2016-01-01	50.4