Year Percent 1986-01-01 0.11031300000000001 1987-01-01 0.33632000000000000 1988-01-01 0.71696200000000000 1989-01-01 0.97901700000000000 1990-01-01 3.47215000000000000 1991-01-01 3.77029000000000000 1992-01-01 2.28672000000000000 1993-01-01 4.46036000000000000 1994-01-01 5.46743000000000000 1995-01-01 4.48767000000000000 1996-01-01 6.40705000000000000 1997-01-01 11.98920000000000000 1998-01-01 16.74000000000000000 1999-01-01 15.23370000000000000 2000-01-01 21.66420000000000000 2001-01-01 25.15530000000000000 2002-01-01 29.19470000000000000 2003-01-01 21.30880000000000000 2004-01-01 13.14940000000000000 2005-01-01 15.74530000000000000 2006-01-01 17.68590000000000000 2007-01-01 18.57750000000000000 2008-01-01 20.65770000000000000 2009-01-01 23.26750000000000000 2010-01-01 25.52270000000000000 2011-01-01 29.50900000000000000 2012-01-01 34.70320000000000000 2013-01-01 33.94460000000000000 2014-01-01 41.00360000000000000 2015-01-01 44.95399999999999000 2016-01-01 47.00680000000000000