************************************************************************ **** Source: M.A.K. Khalil and R. A. Rasmussen **** **** Oregon Graduate Institute of Science and Technology **** **** Portland, Oregon 97291 U.S.A. **** ************************************************************************ 1975 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 110.7 1976 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 126.6 1977 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 140.4 1978 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 151.6 1979 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 161.5 1980 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9 172.9 173.5 174.1 175.1 176.7 171.4 1981 176.9 179.1 179.2 178.4 180.1 180.4 180.9 181.9 181.5 179.2 182.4 184.7 179.9 1982 185.4 186.1 185.8 187.5 186.5 187.8 188.0 190.5 190.7 192.3 192.1 193.6 189.3 1983 195.2 195.4 196.8 196.9 196.7 197.4 197.5 197.4 198.2 199.8 201.2 202.6 198.2 1984 203.8 205.1 205.2 205.4 204.3 204.7 206.0 207.6 208.1 209.1 211.1 212.6 206.8 1985 213.6 212.5 215.3 215.6 216.8 215.8 218.2 218.5 220.6 222.5 223.4 223.9 -99.9 1986 223.0 222.6 223.7 226.4 226.8 227.2 226.3 226.5 229.1 230.5 231.7 232.5 -99.9 1987 233.1 233.4 235.4 236.3 236.8 237.7 237.8 240.0 241.9 243.5 245.7 246.2 -99.9 1988 247.5 248.3 248.9 249.7 250.9 250.4 251.0 252.0 251.7 253.4 254.7 255.9 -99.9 1989 256.2 257.0 256.8 258.6 259.5 259.4 259.0 259.9 261.5 263.4 264.7 265.1 -99.9 1990 265.3 265.3 265.3 265.2 264.9 265.6 266.2 266.1 268.5 268.7 269.8 270.7 -99.9 1991 270.7 270.4 269.5 269.5 270.5 271.1 271.1 271.8 272.9 272.5 273.8 274.4 -99.9 1992 273.9 273.6 274.1 274.1 274.6 273.9 273.6 -99.9 -99.9 -99.9 -99.9 -99.9 -99.9