Whitlock 18Z pressure 1982 - 956.4 946.0 948.3 954.5 947.5 956.8 943.2 942.9 948.0 953.0 963.9 1983 962.9 963.4 953.4 948.6 952.7 955.6 947.7 945.6 949.3 936.9 942.8 955.1 1984 965.0 957.4 948.3 948.7 955.9 947.2 943.2 951.8 948.1 940.8 948.0 963.2 1985 961.5 955.5 953.6 953.4 954.0 950.1 939.3 952.3 940.8 942.2 940.4 949.9 1986 957.8 963.7 959.3 949.5 958.1 958.3 948.4 951.1 945.4 941.5 944.1 952.0 1987 964.6 957.9 954.9 957.1 950.9 955.3 959.9 941.9 956.5 947.1 947.4 956.6 1988 960.0 954.3 953.6 952.9 958.4 962.0 945.8 943.2 952.3 958.7 949.9 952.8 1989 955.3 953.6 952.8 955.7 940.4 949.1 947.4 952.6 950.9 943.6 945.0 959.3 1990 958.9 950.8 954.2 960.8 965.6 955.6 964.5 949.1 940.0 949.9 952.5 954.7 1991 953.0 958.4 950.2 954.8 955.7 958.0 959.3 950.4 949.4 945.6 - 963.3 1992 - - - - - - - - - - - - 1993 - - - - - - - - - - - - 1994 - - - - - - - - - - - - 1995 954.1 954.5 963.6 956.1 952.9 962.0 973.3 959.4 950.4 953.0 952.0 952.0 1996 960.0 963.5 957.4 952.8 959.0 954.8 956.4 - - 945.7 960.7 959.4 1997 962.4 961.1 952.7 959.2 946.8 959.3 - - - - 960.6 964.0 1998 959.1 954.2 955.6 - - - - - - - - - 1999 - - - - - - - - - - - - 2000 - - - - - - - - - - - - 2001 - - 956.7 950.6 956.7 953.3 958.9 953.6 950.8 944.2 948.8 949.7 2002 956.0 950.3 962.1 952.2 963.3 964.6 960.1 949.7 957.7 961.1 955.2 951.4 2003 - - - - - - - - - - - - 2004 - - - - - - - - - - - - 2005 - - - - - - - - - - - - 2006 - - - - - - - - - - - - 2007 - - - - - - - - - - - - 2008 - - - - - - - - - - - - 2009 - - - - - - - - - - - -