Year Percent 1980-01-01 0.19172700000000000 1981-01-01 0.20424100000000000 1982-01-01 0.45662400000000000 1983-01-01 0.79800700000000000 1984-01-01 0.72002000000000000 1985-01-01 0.70561100000000000 1986-01-01 1.06999000000000000 1987-01-01 1.22753000000000000 1988-01-01 1.18062999999999980 1989-01-01 0.88612900000000010 1990-01-01 0.74337100000000000 1991-01-01 0.60893500000000000 1992-01-01 0.46027799999999996 1993-01-01 0.15317800000000000 1994-01-01 0.13539900000000000 1995-01-01 0.11899700000000000 1996-01-01 0.25136200000000000 1997-01-01 0.25506400000000000 1998-01-01 0.51435500000000000 1999-01-01 0.41447399999999995 2000-01-01 0.37043300000000000 2001-01-01 0.21569899999999997 2002-01-01 0.18006100000000000 2003-01-01 0.15234000000000000 2004-01-01 0.48551800000000000 2005-01-01 1.14641000000000000 2006-01-01 1.34513000000000000 2007-01-01 1.44164000000000000 2008-01-01 1.94210999999999980 2009-01-01 2.92791000000000000 2010-01-01 2.56183000000000000 2011-01-01 2.47985000000000000 2012-01-01 3.11422000000000000 2013-01-01 3.48523000000000050 2014-01-01 3.86869000000000000 2015-01-01 5.44799999999999950 2016-01-01 6.08791000000000000