Lettau pressure 1986 - 991.8 990.1 979.4 992.7 990.6 978.6 979.9 976.3 972.0 974.6 981.9 1987 992.5 988.8 985.8 987.7 983.0 986.3 991.7 975.4 988.3 977.4 978.1 985.5 1988 988.7 984.1 985.2 981.4 989.0 995.4 974.9 975.4 982.6 988.6 981.6 983.6 1989 984.7 985.2 982.9 987.4 969.0 979.7 977.5 982.7 981.3 973.3 976.0 989.2 1990 988.7 982.9 985.8 991.3 996.8 985.3 995.7 979.3 970.2 980.6 982.7 983.5 1991 982.4 989.2 980.1 984.1 986.9 989.2 990.6 - - - 983.3 995.1 1992 988.6 994.7 988.0 984.2 989.5 992.9 - - - - 977.5 983.0 1993 996.0 978.6 985.3 981.0 982.6 - - - - - 979.5 984.1 1994 985.0 982.5 977.9 984.6 985.0 997.3 987.1 973.0 987.7 976.9 984.7 981.4 1995 981.2 981.0 991.0 982.0 980.9 986.2 - - - - 977.2 977.7 1996 985.9 - - - - - - - - - - 985.2 1997 - - - - - - - - - - - - 1998 - - 981.7 974.3 982.1 - - - - - - - 1999 - 987.2 983.9 980.4 976.4 999.4 979.1 981.8 981.0 964.1 - - 2000 - - 983.0 982.2 982.3 984.6 979.2 982.5 987.2 975.4 - - 2001 - - 983.4 978.1 983.5 981.4 985.6 981.8 976.2 971.2 - - 2002 - - 989.9 979.8 991.8 993.8 986.8 977.4 985.7 989.9 - - 2003 - - - - - - - - - - - - 2004 - - - - - - - - - - - - 2005 - - 980.5 977.9 978.6 988.1 978.7 974.8 973.0 968.9 - - 2006 - - - - - - - - - - - - 2007 - - - - - - - - - - - - 2008 - - - - - - - - - - - - 2009 - - - - - - - - - - - -