Year	Percent
1991-01-01	41.5950012207031
1992-01-01	41.5250015258789
1993-01-01	43.6259994506836
1994-01-01	42.2589988708496
1995-01-01	38.0639991760254
1996-01-01	28.2819995880127
1997-01-01	30.2360000610352
1998-01-01	24.5300006866455
1999-01-01	22.5489997863770
2000-01-01	20.8519992828369
2001-01-01	23.0550003051758
2002-01-01	23.2660007476807
2003-01-01	26.0039997100830
2004-01-01	22.2999992370605
2005-01-01	20.8530006408691
2006-01-01	20.9479999542236
2007-01-01	18.0440006256104
2008-01-01	19.7129993438721
2009-01-01	24.1889991760254
2010-01-01	25.8260002136230
2011-01-01	27.0049991607666
2012-01-01	28.9440002441406
2013-01-01	29.3659992218018
2014-01-01	33.6930007934570
2015-01-01	32.2929992675781
2016-01-01	29.3199996948242
2017-01-01	28.9500007629395