Year	Percent
1991-01-01	55.8600006103516
1992-01-01	56.9930000305176
1993-01-01	57.2159996032715
1994-01-01	56.9920005798340
1995-01-01	57.8129997253418
1996-01-01	64.7630004882813
1997-01-01	64.7600021362305
1998-01-01	63.2120018005371
1999-01-01	61.6199989318848
2000-01-01	60.8540000915527
2001-01-01	61.7280006408691
2002-01-01	59.9329986572266
2003-01-01	58.5219993591309
2004-01-01	60.1419982910156
2005-01-01	61.7099990844727
2006-01-01	63.6809997558594
2007-01-01	66.6419982910156
2008-01-01	67.7770004272461
2009-01-01	67.9079971313477
2010-01-01	68.7969970703125
2011-01-01	69.4530029296875
2012-01-01	69.5459976196289
2013-01-01	69.7710037231445
2014-01-01	70.5729980468750
2015-01-01	70.3099975585938
2016-01-01	69.4489974975586
2017-01-01	69.4120025634766