Year	Percent
1991-01-01	47.0830001831055
1992-01-01	46.6879997253418
1993-01-01	46.5740013122559
1994-01-01	46.0760002136230
1995-01-01	46.6240005493164
1996-01-01	46.1300010681152
1997-01-01	46.2639999389648
1998-01-01	46.1529998779297
1999-01-01	46.4000015258789
2000-01-01	46.8390007019043
2001-01-01	46.9179992675781
2002-01-01	46.6090011596680
2003-01-01	46.0299987792969
2004-01-01	44.7220001220703
2005-01-01	45.0250015258789
2006-01-01	45.2410011291504
2007-01-01	46.0730018615723
2008-01-01	46.3940010070801
2009-01-01	46.0550003051758
2010-01-01	46.6580009460449
2011-01-01	47.7080001831055
2012-01-01	48.3909988403320
2013-01-01	49.4169998168945
2014-01-01	50.5709991455078
2015-01-01	51.2750015258789
2016-01-01	52.0340003967285
2017-01-01	52.2709999084473