Year	Percent
1999-01-01	23.0192175013418
2000-01-01	20.4750368471381
2001-01-01	15.2179015786652
2002-01-01	16.1486543787379
2003-01-01	15.8410501607443
2004-01-01	14.8223434399287
2005-01-01	11.9936866242544
2006-01-01	11.3473966928483
2007-01-01	10.6985726083690
2008-01-01	12.8233034578044
2009-01-01	18.1258706423283
2010-01-01	20.2235603315201
2011-01-01	21.8118842077037
2012-01-01	25.0330770935257
2013-01-01	26.6706416704811
2014-01-01	25.4250789525897
2015-01-01	23.5478730053874
2016-01-01	21.3789903864058
2017-01-01	19.0280841125526