Year	Percent
1991-01-01	15.8500003814697
1992-01-01	17.2290000915527
1993-01-01	17.1979999542236
1994-01-01	15.9139995574951
1995-01-01	14.8409996032715
1996-01-01	15.4060001373291
1997-01-01	16.2460002899170
1998-01-01	15.1260004043579
1999-01-01	14.0399999618530
2000-01-01	12.6709995269775
2001-01-01	12.8680000305176
2002-01-01	13.6129999160767
2003-01-01	13.6199998855591
2004-01-01	13.4619998931885
2005-01-01	12.4110002517700
2006-01-01	11.6529998779297
2007-01-01	11.1899995803833
2008-01-01	11.5909996032715
2009-01-01	15.3240003585815
2010-01-01	14.9079999923706
2011-01-01	14.2659997940063
2012-01-01	14.4479999542236
2013-01-01	13.7349996566772
2014-01-01	13.4650001525879
2015-01-01	13.1660003662109
2016-01-01	13.0850000381470
2017-01-01	11.6120004653931