Year scale 1-100 1970 55 1971 55 1972 55 1973 55 1974 55 1975 58.125 1976 58.125 1977 60.625 1978 63.75 1979 63.75 1980 63.75 1981 66.25 1982 68.75 1983 71.875 1984 71.875 1985 71.875 1986 71.875 1987 75 1988 75 1989 75 1990 75 1991 75 1992 75 1993 75 1994 78.125 1995 78.125 1996 83.125 1997 85.625 1998 85.625 1999 91.875 2000 95 2001 95 2002 95 2003 95 2004 95 2005 95 2006 95 2007 95 2008 95 2009 95 2010 95 2011 95 2012 95 2013 95 2014 95 2015 95 2016 95 2017 97.5 2018 97.5 2019 97.5 2020 100 2021 100 2022 100 2023 100