Year JAN FEB MAR APR NAY JUN JUL AUG SEP OCT NOV DEC 1961 26.37 26.61 27.00 27.51 27.85 27.84 27.13 26.41 25.96 25.93 26.20 26.20 1962 26.12 26.29 26.80 27.23 27.23 27.17 26.92 26.51 26.07 26.05 25.88 25.75 1963 25.87 26.39 27.31 27.87 27.70 27.68 27.89 27.62 27.45 27.55 27.60 27.70 1964 27.42 27.27 27.11 27.06 26.93 26.65 26.41 25.73 25.48 25.53 25.40 25.41 1965 25.78 26.37 27.13 27.62 28.07 28.19 28.01 28.06 28.02 28.24 28.28 28.05 1966 27.74 27.66 28.21 28.24 27.67 27.77 27.41 26.65 26.48 26.40 26.41 26.20 1967 26.17 26.36 26.67 26.92 27.50 27.61 27.16 26.60 26.09 26.18 26.25 26.09 1968 25.78 25.79 26.38 27.09 27.16 27.69 27.60 27.11 26.89 26.98 27.37 27.42 1969 27.55 27.95 28.02 28.39 28.50 28.00 27.30 27.16 27.33 27.50 27.35 27.31 1970 27.07 27.04 27.37 27.96 27.77 27.13 26.47 25.86 25.86 25.78 25.82 25.47 1971 25.10 25.41 26.11 26.79 27.06 26.70 26.29 25.97 25.93 25.64 25.69 25.55 1972 25.85 26.43 27.22 27.94 28.27 28.23 28.18 28.10 28.09 28.45 28.68 28.80 1973 28.43 27.99 27.72 27.39 27.13 26.74 25.95 25.46 25.32 25.04 24.51 24.44 1974 24.53 25.14 25.93 26.65 26.86 26.72 26.48 26.36 26.22 25.91 25.63 25.70 1975 26.19 26.24 26.46 27.01 26.97 26.30 25.98 25.47 25.20 24.87 25.10 24.76 1976 24.73 25.59 26.61 27.00 27.28 27.35 27.26 27.09 27.12 27.48 27.42 27.16 1977 27.32 27.16 27.58 27.61 27.96 27.95 27.55 26.92 27.20 27.36 27.28 27.36 1978 27.32 27.17 27.24 27.26 27.35 27.16 26.80 26.23 26.20 26.40 26.43 26.49 1979 26.45 26.62 27.48 27.87 27.75 27.55 26.96 26.77 27.15 27.01 27.08 27.09 1980 27.10 27.03 27.38 27.78 27.98 27.99 27.35 26.62 26.57 26.51 26.63 26.59 1981 26.18 26.15 26.77 27.33 27.41 27.35 26.67 26.25 26.53 26.52 26.41 26.48 1982 26.70 26.73 27.36 27.91 28.42 28.32 27.65 27.64 28.20 28.67 28.71 28.93 1983 28.92 28.74 28.76 28.74 28.83 28.27 27.19 26.53 26.19 25.76 25.55 25.82 1984 26.14 26.72 27.05 27.30 27.30 26.95 26.84 26.66 26.43 26.15 25.61 25.38 1985 25.58 26.12 26.54 26.93 27.09 26.92 26.63 26.27 26.08 26.22 26.38 26.19 1986 26.04 26.28 27.01 27.65 27.58 27.56 27.38 27.21 27.35 27.59 27.67 27.74 1987 27.81 28.03 28.50 28.69 28.70 28.66 28.51 28.47 28.41 28.07 27.93 27.60 1988 27.50 27.02 27.46 27.57 26.97 26.20 25.66 25.71 25.72 24.83 24.74 24.68 1989 24.71 25.35 26.13 26.85 27.19 27.24 26.79 26.42 26.46 26.31 26.28 26.58 1990 26.63 27.04 27.41 27.95 28.08 27.63 27.42 27.16 26.96 27.01 26.88 26.97 1991 27.08 27.13 27.39 28.11 28.36 28.41 28.17 27.72 27.41 27.61 27.92 28.30 1992 28.35 28.42 28.65 29.05 29.01 28.35 27.56 26.97 26.67 26.40 26.59 26.71 1993 26.88 27.21 27.72 28.50 28.70 28.08 27.60 27.02 27.14 27.01 26.92 26.79 1994 26.75 26.97 27.52 28.12 28.27 28.09 27.67 27.39 27.25 27.54 27.95 28.01 1995 27.74 27.68 27.92 28.17 27.87 27.80 27.25 26.42 26.20 26.08 25.83 25.87 1996 25.85 25.99 26.75 27.42 27.65 27.49 27.01 26.75 26.44 26.49 26.43 26.12 1997 26.09 26.47 27.15 27.98 28.63 28.86 28.86 28.69 28.89 29.13 29.12 29.04 1998 28.98 28.72 28.67 28.66 28.48 27.42 26.53 25.93 25.66 25.46 25.49 25.13 1999 24.97 25.59 26.45 26.93 27.00 26.67 26.28 25.82 25.76 25.61 25.21 24.97 2000 24.89 25.25 26.29 27.00 27.11 26.97 26.69 26.46 26.32 26.12 26.01 25.84 2001 25.94 26.26 26.91 27.40 27.71 27.61 27.37 26.96 26.75 26.67 26.48 26.33 2002 26.50 26.84 27.50 28.00 28.43 28.48 28.03 27.65 27.73 27.93 28.13 28.09 2003 27.68 27.64 27.85 27.75 27.43 27.57 27.67 27.33 27.11 27.33 27.14 27.07 2004 26.93 27.07 27.42 27.93 28.03 27.94 27.86 27.66 27.58 27.55 27.39 27.40 2005 27.32 27.18 27.64 28.03 28.30 27.99 27.45 27.12 26.80 26.72 26.13 25.81 2006 25.67 26.16 26.82 27.55 27.92 27.83 27.37 27.26 27.33 27.48 27.82 27.87 2007 27.39 27.00 27.27 27.56 27.55 27.54 26.94 26.29 25.97 25.75 25.48 25.39 2008 25.09 25.21 26.18 26.98 27.20 27.15 27.00 26.81 26.70 26.67 26.32 25.89 2009 25.73 26.10 26.80 27.65 28.15 28.12 27.81 27.53 27.53 27.78 28.27 28.47 2010 28.24 28.15 28.33 28.44 28.02 27.23 26.39 25.63 25.31 25.26 25.32 25.29 2011 25.09 25.69 26.39 27.21 27.66 27.64 27.09 26.53 26.17 25.98 25.70 25.61 2012 25.84 26.18 26.93 27.54 27.72 27.69 27.38 27.21 27.58 27.35 27.20 26.23 2013 25.90 26.20 26.88 27.80 27.75