Year Number 2004-01-01 4.1559 2005-01-01 3.9991 2006-01-01 4.0594 2007-01-01 4.3283 2008-01-01 5.7626 2009-01-01 7.1369 2010-01-01 8.5904 2011-01-01 9.5413 2012-01-01 10.0487 2013-01-01 10.3476 2014-01-01 9.1222 2015-01-01 10.1542 2016-01-01 10.1343