Year Percent 1960-01-01 5.4437900000000000 1961-01-01 5.4915699999999990 1962-01-01 6.7051600000000000 1963-01-01 4.7716100000000000 1964-01-01 2.3868800000000000 1965-01-01 2.4502200000000003 1966-01-01 1.6014800000000000 1967-01-01 0.8605770000000000 1968-01-01 5.3445599999999995 1969-01-01 12.0103000000000000 1970-01-01 8.1342300000000000 1971-01-01 8.3700400000000000 1972-01-01 10.1168000000000000 1973-01-01 9.2824500000000000 1974-01-01 12.2837000000000000 1975-01-01 17.9015000000000000 1976-01-01 21.6601000000000000 1977-01-01 17.9274000000000000 1978-01-01 17.4995000000000000 1979-01-01 17.5393000000000000 1980-01-01 18.4198000000000000 1981-01-01 18.7774000000000000 1982-01-01 18.9094000000000000 1983-01-01 18.1925000000000000 1984-01-01 13.8865000000000000 1985-01-01 11.9763000000000000 1986-01-01 13.3143000000000000 1987-01-01 13.5051000000000000 1988-01-01 12.3220000000000010 1989-01-01 10.1528000000000000 1990-01-01 9.4799500000000000 1991-01-01 9.3376100000000000 1992-01-01 9.9487399999999990 1993-01-01 9.8878000000000000 1994-01-01 7.0789800000000005 1995-01-01 6.6090200000000000 1996-01-01 9.0089100000000000 1997-01-01 9.9936100000000000 1998-01-01 11.7259999999999990 1999-01-01 12.8115000000000000 2000-01-01 13.5068000000000000 2001-01-01 12.4052000000000000 2002-01-01 14.0554000000000000 2003-01-01 16.4614000000000000 2004-01-01 17.1880000000000000 2005-01-01 15.5902000000000000 2006-01-01 14.7702000000000000 2007-01-01 15.2081000000000000 2008-01-01 15.2733000000000000 2009-01-01 14.8724000000000000 2010-01-01 15.0438000000000000 2011-01-01 15.4065000000000000 2012-01-01 17.1607000000000000 2013-01-01 17.7585000000000000 2014-01-01 18.9048000000000000 2015-01-01 20.7605000000000000 2016-01-01 22.6212000000000000