Year scale 1-100 1970 23.75 1971 23.75 1972 23.75 1973 23.75 1974 23.75 1975 23.75 1976 23.75 1977 23.75 1978 23.75 1979 23.75 1980 23.75 1981 23.75 1982 23.75 1983 23.75 1984 23.75 1985 23.75 1986 23.75 1987 23.75 1988 23.75 1989 23.75 1990 23.75 1991 23.75 1992 23.75 1993 23.75 1994 23.75 1995 23.75 1996 23.75 1997 23.75 1998 23.75 1999 23.75 2000 23.75 2001 23.75 2002 23.75 2003 23.75 2004 23.75 2005 23.75 2006 23.75 2007 23.75 2008 26.875 2009 26.875 2010 26.875 2011 26.875 2012 26.875 2013 26.875 2014 26.875 2015 26.875 2016 26.875 2017 26.875 2018 26.875 2019 26.875 2020 26.875 2021 26.875 2022 26.875 2023 26.875