Marsh 18Z msl_pressure 1987 - - - - - - - - - - - - 1988 - - - - - - - - - 1000.8 982.5 - 1989 - - - - - - 995.3 - 991.9 983.9 984.7 991.7 1990 - - - 990.6 1003.0 - - - 993.2 - - - 1991 988.2 - - 991.3 - - - - - - - - 1992 - - - - - - - - - - - - 1993 - - - - - - - - - 985.0 985.9 - 1994 985.0 - - 995.2 - - 995.2 990.3 - 989.1 - - 1995 - - - 992.5 - 989.9 989.2 995.1 - 993.6 983.1 - 1996 991.8 990.5 986.9 - - 994.0 991.2 991.5 996.0 - - - 1997 988.4 993.6 990.4 984.7 1000.4 - - - 996.1 991.6 - - 1998 - - 991.3 - 1001.8 996.0 978.9 985.1 991.3 981.1 986.2 983.3 1999 990.0 985.6 996.3 988.7 - 996.8 990.3 989.9 992.0 985.5 987.0 983.6 2000 982.4 995.7 1002.2 - - 997.8 1004.7 992.8 1002.1 - 994.8 989.3 2001 988.9 987.8 - 988.0 999.1 992.2 997.0 981.3 991.5 985.6 980.8 - 2002 - 986.4 992.1 - 993.7 992.0 995.2 999.8 1002.7 989.1 990.8 990.3 2003 993.0 987.0 997.3 993.5 991.4 997.4 984.3 - - 985.3 984.4 994.9 2004 986.9 998.3 989.1 - 995.0 989.1 991.0 991.6 979.5 - - 991.3 2005 986.9 987.4 992.3 984.2 994.7 996.3 997.6 992.0 999.4 993.0 991.3 995.2 2006 - - 981.3 992.6 - - 993.1 999.5 991.9 - 982.3 985.5 2007 989.9 987.7 - 989.9 - - 995.3 987.3 998.2 982.7 990.4 984.9 2008 988.2 989.9 990.9 988.0 993.5 993.2 996.4 992.4 1001.4 - 984.7 982.8 2009 985.5 - - - - - - - - - - -