Year	Percent of Total
1990-01-01	23.7727306062385
1991-01-01	23.5296041077416
1992-01-01	23.2069290286044
1993-01-01	22.8330424190403
1994-01-01	22.4472886855109
1995-01-01	22.0654953836684
1996-01-01	21.5992360006681
1997-01-01	21.2371924546014
1998-01-01	20.9604019657128
1999-01-01	20.7257325524563
2000-01-01	20.4978384978733
2001-01-01	20.1713872686839
2002-01-01	19.8105467883356
2003-01-01	19.4183966258151
2004-01-01	19.0183059754861
2005-01-01	18.6362518619128
2006-01-01	18.3232644256602
2007-01-01	18.0126595830158
2008-01-01	17.7279606732288
2009-01-01	17.4885126527399
2010-01-01	17.2963690109412
2011-01-01	17.1087219941502
2012-01-01	16.9808498039072
2013-01-01	16.8847499751968
2014-01-01	16.7847759162030
2015-01-01	16.6675328314097
2016-01-01	16.5731433593085
2017-01-01	16.4541473628457