Year	Percent
1986-01-01	71.3122908203094
1987-01-01	70.9401295602067
1988-01-01	69.8564249932075
1989-01-01	69.4991487690778
1990-01-01	69.1317669832332
1991-01-01	69.2408858972199
1992-01-01	68.1003763287271
1993-01-01	65.8954038447630
1994-01-01	65.6879447198626
1995-01-01	66.0421223617581
1996-01-01	66.0900560997233
1997-01-01	65.4123057048352
1998-01-01	64.8940309125318
1999-01-01	64.3370067580585
2000-01-01	64.4316524503744
2001-01-01	65.0487784624925
2002-01-01	64.9928356560166
2003-01-01	63.4470545226875
2004-01-01	61.8580279522936
2005-01-01	60.7437563133073
2006-01-01	61.5072365068160
2007-01-01	60.8889303057108
2008-01-01	59.1297175938325
2009-01-01	58.7138340488409
2010-01-01	54.6681524615950
2011-01-01	52.6540987754536
2012-01-01	52.4015865036372
2013-01-01	52.2840545571198
2014-01-01	51.5870961953732
2015-01-01	51.7694238924063
2016-01-01	51.9686449732808
2017-01-01	51.4674429891942