Year Percent 1970 0.98788 1980 0.9988 1982 1.01094 1983 1.01132 1984 1.02799 1991 1.04301 2006 1.06209 2007 1.0728 2008 1.07486 2010 1.06988 2011 1.06585 2012 1.06463 2013 1.06036 2014 1.0437 2015 1.05813 2016 1.05075