Year	Percent
1986-01-01	36.8564687837874
1987-01-01	36.3551871732388
1988-01-01	37.0893588480670
1989-01-01	38.3271213240276
1990-01-01	37.0222288348962
1991-01-01	36.5496465718028
1992-01-01	36.6946914469617
1993-01-01	36.6924149184052
1994-01-01	35.4376298945034
1995-01-01	34.4070303302070
1996-01-01	32.9090408644108
1997-01-01	33.0627135801645
1998-01-01	33.2514405210763
1999-01-01	32.9409561209051
2000-01-01	32.8183353744714
2001-01-01	31.8482674022708
2002-01-01	31.1947752883072
2003-01-01	31.0293829154076
2004-01-01	30.7946198446627
2005-01-01	29.6210794176667
2006-01-01	29.0237912644785
2007-01-01	28.5668273668348
2008-01-01	28.4017320886948
2009-01-01	28.4801972683971
2010-01-01	28.7736029681631
2011-01-01	28.3590485712870
2012-01-01	28.1914358675270
2013-01-01	27.4717890662930
2014-01-01	26.2908348179335
2015-01-01	26.3229177917144
2016-01-01	25.0775674486499
2017-01-01	23.8411824136986