Year Percent 1988-01-01 0.3919690000000000 1989-01-01 0.8310750000000000 1990-01-01 0.8703670000000000 1991-01-01 1.0745100000000000 1992-01-01 1.9192200000000001 1993-01-01 2.8323500000000000 1994-01-01 4.2851000000000000 1995-01-01 3.8680900000000000 1996-01-01 3.5841900000000000 1997-01-01 3.3773400000000002 1998-01-01 3.5486300000000000 1999-01-01 4.6335600000000000 2000-01-01 6.0633000000000000 2001-01-01 7.3484000000000000 2002-01-01 7.9512600000000000 2003-01-01 7.6157200000000000 2004-01-01 6.4637100000000000 2005-01-01 5.6848199999999990 2006-01-01 6.1631500000000000 2007-01-01 5.6751700000000000 2008-01-01 4.9822900000000000 2009-01-01 6.1930200000000000 2010-01-01 5.6690100000000000 2011-01-01 5.3218100000000000 2012-01-01 5.9407100000000000 2013-01-01 6.0519300000000005 2014-01-01 6.5404700000000000 2015-01-01 6.9513300000000005 2016-01-01 7.1203400000000000