Year JAN FEB MAR APR NAY JUN JUL AUG SEP OCT NOV DEC 1950 27.70 27.82 27.99 28.23 28.35 28.31 27.90 27.72 27.73 27.99 28.21 27.99 1951 27.84 27.83 27.99 28.24 28.30 28.03 27.76 27.48 27.77 28.10 28.11 28.03 1952 27.87 27.90 28.00 28.33 28.31 28.07 27.66 27.48 27.82 28.02 28.02 27.89 1953 27.82 27.84 28.04 28.32 28.33 28.21 27.89 27.67 27.66 27.98 28.24 28.14 1954 28.01 27.99 28.07 28.34 28.25 28.08 27.84 27.79 27.78 27.99 28.02 27.83 1955 27.75 27.68 27.88 28.11 28.20 28.06 27.80 27.83 27.97 27.96 28.02 27.94 1956 27.77 27.69 27.95 28.22 28.30 28.16 27.95 27.67 27.78 28.10 28.28 28.08 1957 27.91 27.76 27.94 28.34 28.55 28.25 27.86 27.71 27.73 28.01 28.15 28.03 1958 27.97 27.99 28.16 28.40 28.43 28.21 27.94 27.85 27.97 28.13 28.13 28.01 1959 27.76 27.87 28.04 28.36 28.49 28.23 27.95 27.79 27.85 28.09 28.26 28.18 1960 27.92 27.81 28.16 28.37 28.58 28.21 27.98 27.74 27.95 28.13 28.42 28.22 1961 27.94 28.00 28.15 28.38 28.39 28.15 27.78 27.64 27.75 28.02 28.26 28.16 1962 28.00 27.84 28.12 28.47 28.50 28.44 28.17 28.00 28.09 28.38 28.41 28.24 1963 27.99 27.85 28.18 28.49 28.61 28.36 28.00 27.87 28.02 28.11 28.38 28.28 1964 28.12 28.00 28.17 28.48 28.52 28.31 28.05 27.82 27.98 28.13 28.07 27.83 1965 27.65 27.69 27.78 28.12 28.21 27.96 27.55 27.53 27.64 27.80 28.02 27.98 1966 27.82 27.94 28.17 28.41 28.34 28.14 27.91 27.74 27.90 28.10 28.29 28.14 1967 27.86 27.76 27.91 28.33 28.51 28.29 27.84 27.76 27.88 28.05 28.08 27.99 1968 27.76 27.65 27.93 28.27 28.42 28.51 28.17 27.96 28.06 28.27 28.34 28.26 1969 28.06 27.98 28.21 28.59 28.72 28.48 28.14 28.00 28.18 28.34 28.47 28.34 1970 28.16 28.09 28.39 28.56 28.65 28.43 28.18 27.99 28.16 28.38 28.50 28.26 1971 28.03 27.88 28.01 28.26 28.42 28.20 27.88 27.88 28.08 28.21 28.22 28.04 1972 27.88 27.95 27.97 28.26 28.31 28.07 27.71 27.59 27.78 28.13 28.31 28.25 1973 28.14 28.12 28.28 28.55 28.64 28.50 28.21 28.17 28.26 28.34 28.41 28.26 1974 27.75 27.75 27.90 28.24 28.44 28.18 28.04 27.92 28.06 28.26 28.32 28.13 1975 27.96 27.88 28.13 28.30 28.49 28.17 28.01 27.88 28.01 28.12 28.14 27.96 1976 27.77 27.68 27.91 28.31 28.31 28.04 27.69 27.61 27.67 28.15 28.31 28.17 1977 27.96 27.94 27.97 28.35 28.53 28.29 27.86 27.75 27.84 28.03 28.20 28.12 1978 28.03 27.89 28.21 28.42 28.51 28.40 28.16 27.86 27.94 28.01 28.19 28.15 1979 27.97 28.01 28.24 28.46 28.50 28.29 27.92 27.76 27.90 28.12 28.38 28.21 1980 28.03 27.95 28.31 28.43 28.57 28.39 28.08 27.88 28.01 28.26 28.44 28.35 1981 27.96 27.94 28.18 28.52 28.69 28.46 28.22 27.98 28.11 28.40 28.48 28.28 1982 28.03 27.93 28.14 28.42 28.55 28.23 27.78 27.66 27.75 28.04 28.27 28.29 1983 28.03 27.98 28.23 28.58 28.62 28.46 27.99 27.86 28.14 28.36 28.44 28.20 1984 28.05 28.00 28.18 28.50 28.67 28.33 28.08 27.90 28.19 28.26 28.43 28.19 1985 27.97 28.09 28.26 28.49 28.54 28.28 27.99 27.81 27.98 28.26 28.43 28.36 1986 28.00 27.96 28.12 28.49 28.62 28.42 28.10 27.86 27.84 28.24 28.31 28.12 1987 27.98 27.82 28.16 28.47 28.65 28.37 28.04 27.95 28.08 28.37 28.62 28.37 1988 28.27 28.38 28.58 28.77 28.83 28.57 28.36 28.30 28.45 28.57 28.48 28.17 1989 28.14 27.98 28.19 28.57 28.66 28.43 28.26 28.08 28.32 28.48 28.48 28.24 1990 28.08 28.18 28.32 28.62 28.76 28.48 28.23 28.07 28.09 28.41 28.51 28.33 1991 28.11 27.98 28.16 28.54 28.63 28.48 28.23 28.08 28.06 28.16 28.22 28.13 1992 27.89 27.99 28.13 28.51 28.65 28.51 28.12 28.02 28.12 28.19 28.15 28.03 1993 27.75 27.61 27.97 28.25 28.36 28.33 28.00 27.82 27.94 28.06 28.40 28.21 1994 27.97 28.06 28.22 28.51 28.60 28.38 28.00 27.90 27.92 28.15 28.34 28.32 1995 28.09 28.06 28.27 28.65 28.76 28.64 28.38 28.33 28.30 28.53 28.73 28.46 1996 28.16 28.13 28.38 28.71 28.73 28.69 28.53 28.37 28.46 28.70 28.72 28.52 1997 28.15 28.11 28.30 28.62 28.67 28.51 28.08 27.77 27.98 28.30 28.41 28.51 1998 28.20 28.36 28.56 28.89 28.99 28.82 28.65 28.56 28.62 28.76 28.89 28.61 1999 28.45 28.34 28.59 28.80 28.74 28.54 28.21 28.04 28.28 28.52 28.59 28.47 2000 28.30 28.20 28.32 28.71 28.78 28.46 28.18 28.22 28.37 28.61 28.76 28.52 2001 28.40 28.31 28.56 28.93 29.02 28.83 28.46 28.24 28.40 28.69 28.75 28.56 2002 28.40 28.30 28.56 29.04 29.12 28.89 28.44 28.19 28.24 28.47 28.71 28.70 2003 28.43 28.39 28.58 28.91 28.99 28.71 28.47 28.25 28.39 28.67 28.73 28.50 2004 28.35 28.38 28.62 28.92 28.95 28.57 28.33 28.06 28.29 28.46 28.68 28.57 2005 28.31 28.40 28.59 28.78 28.91 28.78 28.50 28.33 28.41 28.70 28.80 28.65 2006 28.39 28.24 28.43 28.77 28.92 28.74 28.24 28.04 28.21 28.29 28.60 28.56 2007 28.35 28.26 28.44 28.73 28.84 28.79 28.43 28.25 28.40 28.57 28.59 28.52 2008 28.29 28.17 28.34 28.68 28.64 28.40 28.20 28.17 28.39 28.66 28.75 28.65 2009 28.35 28.21 28.56 28.86 28.89 28.80 28.59 28.43 28.39 28.54 28.69 28.52 2010 28.28 28.32 28.62 28.95 29.14 28.94 28.64 28.42 28.55 28.74 28.88 28.74 2011 28.37 28.26 28.43 28.73 28.92 28.68 28.26 28.13 28.22 28.48 28.75 28.62 2012 28.36 28.34 28.47 28.81 28.88 28.51 28.24 28.02 28.26 28.49 28.76 28.73 2013 28.47 28.48 28.58 28.93 29.06