Year	Percent
1991-01-01	50.6819992065430
1992-01-01	46.9370002746582
1993-01-01	53.0979995727539
1994-01-01	51.4239997863770
1995-01-01	56.4290008544922
1996-01-01	50.3079986572266
1997-01-01	54.1650009155273
1998-01-01	59.2290000915527
1999-01-01	33.8740005493164
2000-01-01	29.8570003509521
2001-01-01	36.1870002746582
2002-01-01	43.1409988403320
2003-01-01	39.4360008239746
2004-01-01	47.8810005187988
2005-01-01	47.7589988708496
2006-01-01	46.0519981384277
2007-01-01	46.5519981384277
2008-01-01	47.6629981994629
2009-01-01	46.2169990539551
2010-01-01	36.3079986572266
2011-01-01	38.8610000610352
2012-01-01	32.9169998168945
2013-01-01	34.5309982299805
2014-01-01	34.8800010681152
2015-01-01	37.9720001220703
2016-01-01	38.9589996337891
2017-01-01	38.5330009460449