Year Percent 1980-01-01 9.903490000000000 1981-01-01 9.703110000000000 1982-01-01 11.047200000000000 1983-01-01 11.517600000000000 1984-01-01 11.173800000000000 1985-01-01 12.102200000000000 1986-01-01 11.808100000000000 1987-01-01 10.397900000000000 1988-01-01 8.880930000000001 1989-01-01 7.517280000000000 1990-01-01 7.622650000000000 1991-01-01 8.843370000000000 1992-01-01 9.516290000000000 1993-01-01 9.584489999999999 1994-01-01 8.465539999999999 1995-01-01 7.938470000000000 1996-01-01 7.748520000000000 1997-01-01 7.575960000000000 1998-01-01 7.101070000000000 1999-01-01 7.003970000000000 2000-01-01 6.347830000000000 2001-01-01 6.055969999999999 2002-01-01 6.340490000000000 2003-01-01 5.550950000000000 2004-01-01 4.918120000000000 2005-01-01 4.756080000000000 2006-01-01 4.793710000000000 2007-01-01 6.021160000000000 2008-01-01 8.717340000000000 2009-01-01 9.336190000000000 2010-01-01 8.997310000000000 2011-01-01 9.132240000000000 2012-01-01 9.673969999999999 2013-01-01 9.489150000000000 2014-01-01 9.703850000000000 2015-01-01 10.098400000000000 2016-01-01 11.834600000000000