1991-2020 Degrees Fahrenheit 1 45.6 46.0 -0.4 33 44 1960 2012 1984 1991 normal 2 43.8 42.1 1.7 64 13 1960 1976 1989 1991 top-third 1949,2011,2022 3 41.1 39.8 1.3 58 19 1978 1990 1988 1991 top-third 2002 4 41.2 39.5 1.7 61 16 1978 2012 1990 1991 top-third 1972 5 42.2 40.9 1.3 63 13 1977 2012 1990 1991 top-third 1989 6 45.0 43.6 1.4 62 14 1977 2012 1990 1991 top-third 1986 7 48.4 47.1 1.3 64 11 1977 2017 1990 1991 top-third 1986 8 51.8 50.6 1.2 65 10 1977 2017 1991 1976 top-third 9 54.7 53.3 1.4 68 7 1977 2017 1991 1976 top-tenth 1972,1976 10 56.6 55.2 1.4 66 9 1977 2017 1991 1974 top-third 11 58.0 56.1 1.9 70 5 1977 2017 1991 1992 top-tenth 12 58.2 56.2 2.0 71 4 1977 2012,2017,2020 1991 1992 top-tenth 2016 18 54.0 51.9 2.1 73 2 1978 2017 1991 1992 top-tenth 24 57.3 56.1 1.2 68 6 1978 2017 1991 1992 top-tenth 2013 36 56.7 56.1 0.6 65 8 1979 2018 1991 1992 top-third 48 56.6 56.1 0.5 65 7 1980 2020 1991 1992 top-tenth 2008 60 56.5 56.0 0.5 65 6 1981 2020 1991 1992 top-tenth 2012