Year Percent 1962-01-01 21.358900000000000 1963-01-01 19.244300000000000 1964-01-01 16.643100000000000 1965-01-01 15.430600000000000 1966-01-01 14.188100000000000 1967-01-01 12.808700000000000 1968-01-01 13.051500000000000 1969-01-01 13.957900000000000 1970-01-01 17.269900000000000 1971-01-01 18.800000000000000 1972-01-01 17.872700000000000 1973-01-01 20.234900000000000 1974-01-01 21.570200000000000 1975-01-01 20.306800000000000 1976-01-01 20.987400000000000 1977-01-01 24.408900000000000 1978-01-01 27.518300000000000 1979-01-01 26.743700000000000 1980-01-01 23.524300000000000 1981-01-01 22.672600000000000 1982-01-01 24.015800000000000 1983-01-01 25.469200000000000 1984-01-01 23.965600000000000 1985-01-01 22.784700000000000 1986-01-01 22.185600000000000 1987-01-01 21.592600000000000 1988-01-01 22.507300000000000 1989-01-01 22.759000000000000 1990-01-01 23.569200000000000 1991-01-01 22.894800000000000 1992-01-01 23.873100000000000 1993-01-01 22.373600000000000 1994-01-01 20.657500000000000 1995-01-01 19.958000000000000 1996-01-01 20.323400000000000 1997-01-01 20.814300000000000 1998-01-01 20.371600000000000 1999-01-01 21.191600000000000 2000-01-01 22.480999999999998 2001-01-01 23.692400000000000 2002-01-01 25.157400000000000 2003-01-01 28.131700000000000 2004-01-01 32.078900000000000 2005-01-01 32.811000000000000 2006-01-01 33.714900000000000 2007-01-01 34.510700000000000 2008-01-01 33.685300000000000 2009-01-01 34.629500000000000 2010-01-01 37.172700000000000 2011-01-01 38.579400000000000 2012-01-01 38.284600000000000 2013-01-01 40.731200000000000 2014-01-01 43.111400000000000 2015-01-01 45.517500000000000 2016-01-01 46.132500000000000