Year	Index
1997-01-01	53.7
1998-01-01	56.1
1999-01-01	56.3
2000-01-01	49.4
2001-01-01	51.5
2002-01-01	53.8
2003-01-01	53.5
2004-01-01	50.3
2005-01-01	50.8
2006-01-01	50.5
2007-01-01	50.4
2008-01-01	47.8
2009-01-01	47.3
2010-01-01	45.7
2011-01-01	44.9
2012-01-01	44.7
2013-01-01	44.1
2014-01-01	43.4
2015-01-01	43.5
2016-01-01	43.8