Year	Percent
1991-01-01	34.1629981994629
1992-01-01	33.6419982910156
1993-01-01	35.9869995117188
1994-01-01	28.9529991149902
1995-01-01	36.1839981079102
1996-01-01	35.9620018005371
1997-01-01	37.0040016174316
1998-01-01	36.1319999694824
1999-01-01	36.1240005493164
2000-01-01	35.7830009460449
2001-01-01	34.4879989624023
2002-01-01	33.1269989013672
2003-01-01	21.9990005493164
2004-01-01	27.8320007324219
2005-01-01	25.1019992828369
2006-01-01	22.4400005340576
2007-01-01	21.6959991455078
2008-01-01	24.6480007171631
2009-01-01	26.5380001068115
2010-01-01	28.8959999084473
2011-01-01	29.7150001525879
2012-01-01	34.3240013122559
2013-01-01	36.1609992980957
2014-01-01	32.8899993896484
2015-01-01	31.4379997253418
2016-01-01	31.3619995117188
2017-01-01	29.7350006103516