Year	Percent
1991-01-01	46.1160011291504
1992-01-01	46.6720008850098
1993-01-01	46.1370010375977
1994-01-01	46.6240005493164
1995-01-01	46.9550018310547
1996-01-01	47.2470016479492
1997-01-01	47.0950012207031
1998-01-01	47.2560005187988
1999-01-01	47.0620002746582
2000-01-01	47.3590011596680
2001-01-01	46.8790016174316
2002-01-01	47.4220008850098
2003-01-01	48.0439987182617
2004-01-01	48.2919998168945
2005-01-01	48.2830009460449
2006-01-01	49.0499992370605
2007-01-01	49.3009986877441
2008-01-01	49.6419982910156
2009-01-01	49.0460014343262
2010-01-01	47.4920005798340
2011-01-01	44.2080001831055
2012-01-01	40.5079994201660
2013-01-01	38.6879997253418
2014-01-01	38.9469985961914
2015-01-01	39.8680000305176
2016-01-01	40.6450004577637
2017-01-01	41.5069999694824