Year Percent 1980-01-01 0.038998000000000005 1981-01-01 0.035410000000000004 1982-01-01 0.044940000000000000 1983-01-01 0.040839000000000000 1984-01-01 0.042017000000000000 1985-01-01 0.058396000000000000 1986-01-01 0.058991999999999996 1987-01-01 0.072265000000000000 1988-01-01 0.084695000000000000 1989-01-01 0.104607999999999990 1990-01-01 0.125105000000000000 1991-01-01 0.123942000000000010 1992-01-01 0.122513000000000010 1993-01-01 0.103415000000000000 1994-01-01 0.102029000000000000 1995-01-01 0.097380000000000000 1996-01-01 0.117425000000000000 1997-01-01 0.127508999999999980 1998-01-01 0.130827000000000000 1999-01-01 0.114936999999999980 2000-01-01 0.096965000000000000 2001-01-01 0.100872000000000000 2002-01-01 0.095575000000000000 2003-01-01 0.076727000000000000 2004-01-01 0.057584000000000000 2005-01-01 0.056509000000000004 2006-01-01 0.052787000000000000 2007-01-01 0.046870000000000000 2008-01-01 0.049586000000000000 2009-01-01 0.048860000000000000 2010-01-01 0.043585000000000006 2011-01-01 0.037147000000000000 2012-01-01 0.061169000000000010 2013-01-01 0.091346000000000010 2014-01-01 0.112511999999999990 2015-01-01 0.146507000000000000 2016-01-01 0.149011999999999980