Year,Jan.,Feb.,Mar.,Apr.,May,Jun.,Jul.,Aug.,Sept.,Oct.,Nov.,Dec.,Mean
1965,23.67,25.77,26.39,26.72,26.89,25.45,23.58,23.03,23.05,23.18,23.81,24.39,24.66
1966,25.93,25.95,24.44,23.62,22.54,22.17,21.75,20.92,21.54,21.57,22.41,22.37,22.93
1967,24.26,24.84,24.58,24.39,23.24,22.94,21.79,20.82,20.00,21.25,22.05,21.93,22.67
1968,22.96,24.13,23.49,23.24,22.45,21.43,22.26,22.65,23.02,23.11,23.08,23.79,22.97
1969,24.48,25.59,27.22,27.56,26.80,25.56,22.59,21.99,22.29,23.31,23.66,24.65,24.64
1970,24.75,24.63,24.04,24.34,22.95,21.02,19.98,19.95,20.83,21.27,22.72,22.43,22.41
1971,23.66,24.58,25.52,26.35,24.04,22.93,22.46,21.61,21.32,22.50,22.93,22.40,23.36
1972,24.12,25.87,26.06,27.71,26.31,24.75,24.27,23.97,23.52,23.52,24.13,25.61,24.99
1973,26.99,25.96,25.33,23.46,21.87,20.71,20.83,20.43,20.61,20.52,21.71,22.37,22.57
1974,23.09,25.13,24.28,25.82,25.02,23.89,21.95,21.03,21.17,20.92,21.34,20.78,22.87
1975,22.96,25.55,26.19,26.36,23.53,22.30,21.66,20.94,20.70,20.40,20.53,21.34,22.71
1976,23.30,24.20,25.01,26.12,26.50,25.41,24.61,23.98,22.81,22.63,23.62,24.25,24.37
1977,25.62,25.48,24.53,24.12,23.76,22.90,21.94,20.85,20.54,22.00,22.89,23.59,23.18
1978,25.06,25.96,25.42,23.76,22.93,20.93,21.32,20.48,20.14,21.55,22.25,23.23,22.75
1979,25.37,25.26,25.24,26.59,24.46,23.36,22.55,21.93,22.47,22.46,23.16,23.41,23.85
1980,24.70,25.43,24.96,25.43,24.38,22.93,22.45,21.14,20.99,21.62,22.61,22.57,23.27
1981,23.11,24.46,24.87,25.48,24.59,23.28,22.08,20.26,21.10,21.27,21.51,23.31,22.94
1982,24.28,25.39,25.40,24.95,25.29,24.24,23.82,23.17,23.40,24.18,25.94,26.92,24.75
1983,27.57,27.89,28.56,28.54,27.94,27.50,26.75,24.31,22.28,22.41,22.44,23.22,25.78
1984,,,,24.82,23.13,22.09,21.98,21.47,21.76,22.21,22.62,23.16,22.58
1985,23.66,23.58,24.11,25.02,22.65,22.48,22.34,21.43,21.13,21.44,22.39,22.70,22.74
1986,24.14,25.62,25.47,24.79,24.75,22.96,22.81,22.55,21.84,22.25,23.47,24.15,23.73
1987,25.84,27.37,27.48,27.95,26.59,24.42,22.89,23.00,23.31,23.09,23.60,23.89,24.95
1988,24.15,24.56,24.54,22.68,21.58,19.96,18.96,19.83,20.98,20.25,21.60,22.09,21.77
1989,23.41,25.23,24.52,25.82,24.59,23.03,21.81,22.16,21.50,21.83,22.08,22.22,23.18
1990,23.94,26.25,25.07,26.16,25.22,23.31,21.78,21.39,21.47,21.43,23.01,23.25,23.52
1991,23.85,26.37,26.82,23.44,25.21,24.69,23.50,22.35,22.28,22.55,23.23,24.43,24.06
1992,25.81,27.52,27.78,28.38,26.82,23.65,21.65,21.45,21.11,21.53,22.03,23.19,24.24
1993,24.15,26.14,26.37,27.40,26.52,24.88,23.47,21.64,21.66,22.10,22.96,23.32,24.22
1994,24.61,25.20,23.51,22.32,22.50,23.13,22.16,21.35,21.08,22.11,23.51,24.56,23.00
1995,26.28,25.78,25.30,22.43,22.44,22.11,21.70,20.69,21.20,21.56,22.13,21.97,22.80
1996,23.44,24.84,25.59,23.22,22.37,21.35,21.24,20.71,20.09,20.97,21.45,21.27,22.21
1997,23.05,25.36,26.71,27.13,27.03,26.71,26.48,25.91,25.83,25.98,26.65,27.75,26.21
1998,27.87,27.85,28.47,28.46,26.89,25.80,23.09,21.99,20.98,21.05,22.45,21.63,24.71
,,,,,,,,,,,,,
Mean,24.55,25.57,25.55,25.43,24.52,23.36,22.49,21.81,21.71,22.06,22.82,23.30,
,,,,,,,,,,,,,
Median,24.15,25.48,25.33,25.46,24.52,23.08,22.21,21.46,21.40,21.91,22.67,23.22,
,,,,,,,,,,,,,
Standard Deviation,1.32,1.02,1.32,1.84,1.81,1.75,1.53,1.35,1.21,1.15,1.20,1.50,
,,,,,,,,,,,,,
Coefficient of Variation,5.39,4.00,5.15,7.23,7.37,7.50,6.79,6.19,5.57,5.23,5.25,6.43,