Year Percent 1973-01-01 9.36105 1974-01-01 8.93256 1975-01-01 9.60341 1976-01-01 10.41620 1977-01-01 13.13650 1978-01-01 16.23030 1979-01-01 17.47460 1980-01-01 15.75340 1981-01-01 14.51790 1982-01-01 16.18630 1983-01-01 16.78080 1984-01-01 16.68250 1985-01-01 17.43740 1986-01-01 17.52120 1987-01-01 17.65000 1988-01-01 19.22520 1989-01-01 18.83580 1990-01-01 17.96150 1991-01-01 14.13050 1992-01-01 9.71461 1993-01-01 9.98025 1994-01-01 11.01530 1995-01-01 19.35120 1996-01-01 27.21200 1997-01-01 25.96960 1998-01-01 26.80660 1999-01-01 27.94880 2000-01-01 27.16020 2001-01-01 29.65240 2002-01-01 30.05090 2003-01-01 29.31800 2004-01-01 28.92280 2005-01-01 31.08290 2006-01-01 33.57290 2007-01-01 33.74110 2008-01-01 32.73910 2009-01-01 30.44250 2010-01-01 29.60740 2011-01-01 33.96920 2012-01-01 36.36090 2013-01-01 39.62440 2014-01-01 39.72250 2015-01-01 43.62670 2016-01-01 56.38950