Year Percent 1960-01-01 1.8848400000000000 1961-01-01 1.8393800000000000 1962-01-01 1.7935500000000000 1963-01-01 2.1138800000000000 1964-01-01 2.1495900000000003 1965-01-01 2.1579200000000003 1966-01-01 2.1395100000000000 1967-01-01 2.5208200000000000 1968-01-01 2.6486400000000003 1969-01-01 3.0456600000000000 1970-01-01 3.9103700000000000 1971-01-01 4.7958000000000000 1972-01-01 5.6047900000000000 1973-01-01 7.3434000000000000 1974-01-01 7.0993699999999995 1975-01-01 6.4672300000000010 1976-01-01 7.9607500000000000 1977-01-01 10.6622000000000000 1978-01-01 11.3159999999999990 1979-01-01 11.7689000000000000 1980-01-01 13.6206000000000000 1981-01-01 13.9615000000000000 1982-01-01 15.1994000000000000 1983-01-01 17.4450000000000000 1984-01-01 16.8712000000000000 1985-01-01 16.7083000000000000 1986-01-01 17.5507000000000000 1987-01-01 17.9447000000000000 1988-01-01 18.2808000000000000 1989-01-01 19.6041000000000000 1990-01-01 20.3265000000000000 1991-01-01 20.9113000000000000 1992-01-01 20.9531000000000000 1993-01-01 22.4970000000000000 1994-01-01 23.3512000000000000 1995-01-01 24.8825000000000000 1996-01-01 25.4519999999999980 1997-01-01 25.6358000000000000 1998-01-01 29.9146000000000000 1999-01-01 32.5045000000000000 2000-01-01 35.2272000000000000 2001-01-01 35.7609999999999960 2002-01-01 37.8309000000000000 2003-01-01 38.6046000000000000 2004-01-01 39.2509000000000000 2005-01-01 40.1944000000000000 2006-01-01 41.3481000000000000 2007-01-01 44.4524000000000000 2008-01-01 48.7128000000000000 2009-01-01 55.3463000000000000 2010-01-01 58.4283000000000000 2011-01-01 59.1524000000000000 2012-01-01 62.3145000000000000 2013-01-01 65.5465000000000000 2014-01-01 67.3665000000000000 2015-01-01 73.2119000000000000 2016-01-01 84.4024000000000000