Year Percent 1980-01-01 6.3512699999999995 1981-01-01 8.5177000000000000 1982-01-01 9.1061400000000000 1983-01-01 8.5315000000000000 1984-01-01 9.3542300000000010 1985-01-01 11.7635000000000000 1986-01-01 10.7250000000000000 1987-01-01 11.2219000000000000 1988-01-01 10.4829999999999990 1989-01-01 11.2053000000000000 1990-01-01 11.0134000000000000 1991-01-01 11.6401000000000000 1992-01-01 10.6132000000000000 1993-01-01 11.0576000000000000 1994-01-01 11.4316000000000000 1995-01-01 11.5704000000000000 1996-01-01 11.8301000000000000 1997-01-01 13.5307000000000000 1998-01-01 15.7317000000000000 1999-01-01 16.9402000000000000 2000-01-01 23.3754000000000000 2001-01-01 27.5251000000000000 2002-01-01 33.6513000000000000 2003-01-01 37.1287000000000000 2004-01-01 40.4593000000000000 2005-01-01 42.3929000000000000 2006-01-01 53.2103000000000000 2007-01-01 60.3007000000000000 2008-01-01 56.1436000000000000 2009-01-01 62.7887000000000000 2010-01-01 60.0541000000000000 2011-01-01 51.6179000000000000 2012-01-01 52.2540000000000000 2013-01-01 49.4178000000000000 2014-01-01 39.1311000000000000 2015-01-01 39.3506000000000000 2016-01-01 34.3256000000000000