Year Percent 1960-01-01 0.27631300000000003 1961-01-01 0.62750800000000000 1962-01-01 1.14905000000000000 1963-01-01 1.68730000000000000 1964-01-01 2.24142000000000000 1965-01-01 2.16157000000000000 1966-01-01 2.66249000000000000 1967-01-01 4.80772000000000000 1968-01-01 6.33212000000000000 1969-01-01 4.85498000000000000 1970-01-01 3.02680000000000000 1971-01-01 2.93369000000000040 1972-01-01 2.53043000000000000 1973-01-01 1.75921000000000000 1974-01-01 0.58305500000000000 1975-01-01 0.88301800000000010 1976-01-01 1.82754000000000020 1977-01-01 3.76828000000000030 1978-01-01 7.31491000000000000 1979-01-01 7.10582000000000000 1980-01-01 5.56688000000000000 1981-01-01 8.94759000000000000 1982-01-01 13.37980000000000000 1983-01-01 17.34460000000000000 1984-01-01 19.61750000000000000 1985-01-01 15.87870000000000000 1986-01-01 19.58580000000000000 1987-01-01 16.49460000000000000 1988-01-01 17.12840000000000000 1989-01-01 16.01340000000000000 1990-01-01 8.51464000000000000 1991-01-01 11.06660000000000000 1992-01-01 13.07560000000000000 1993-01-01 15.26340000000000000 1994-01-01 15.07930000000000000 1995-01-01 13.85090000000000000 1996-01-01 10.75410000000000000 1997-01-01 8.96032000000000000 1998-01-01 9.54133000000000000 1999-01-01 9.52358000000000000 2000-01-01 7.76709000000000000 2001-01-01 8.01068000000000000 2002-01-01 5.88723000000000100 2003-01-01 4.24170000000000000 2004-01-01 2.98057000000000000 2005-01-01 1.86897999999999990 2006-01-01 1.79450999999999980 2007-01-01 2.99063000000000000 2008-01-01 2.76794000000000030 2009-01-01 1.39134000000000000 2010-01-01 1.07028000000000000 2011-01-01 1.16963000000000000 2012-01-01 1.03214000000000000 2013-01-01 0.92794900000000000 2014-01-01 0.93864900000000000 2015-01-01 2.08957999999999980 2016-01-01 4.32763000000000000