Year	Percent
1997-01-01	19.9881
1998-01-01	32.8611
1999-01-01	19.9881
2000-01-01	22.7017
2001-01-01	23.1363
2002-01-01	58.3923
2003-01-01	55.9716
2004-01-01	46.1497
2005-01-01	40.7852
2006-01-01	31.1293
2007-01-01	45.5963
2008-01-01	28.6199
2009-01-01	35.8695
2010-01-01	37.2340
2011-01-01	35.8951
2012-01-01	30.0545
2013-01-01	33.0922
2014-01-01	42.0925