Year Percent 1966 6.70589 1967 6.47085 1968 6.76637 1969 6.76976 1970 6.64963 1971 6.61773 1972 7.11026 1973 5.70548 1974 4.58177 1975 5.03575 1976 4.87316 1977 4.10206 1978 3.65163 1979 3.36055 1980 2.58787 1981 2.59698 1982 2.3888 1983 2.1317 1984 1.32674 1985 2.43484 1986 2.76304 1987 2.76806 1988 2.71623 1989 2.45033 1990 2.54097 1991 2.4771 1992 2.53568 1993 2.51492 1994 2.22232 1995 2.31283 1996 2.08491 1997 2.16723 1998 2.05806 1999 1.93592 2000 1.35719 2001 1.28638 2002 1.39847 2003 0.94788 2004 0.76148 2005 0.484 2006 0.56688 2007 0.37166 2008 0.36551 2009 0.59515 2010 0.52015 2011 0.45654 2012 1.31812 2013 1.25708 2014 1.44292 2015 1.65829 2016 1.61809 2017 1.72011 2018 1.70198 2019 1.58506 2020 1.777 2021 1.47095 2022 1.07696