+-----------------------------+--------------+-------------------------+
|                             | pressure     | standard deviation of   |
|                             |              | pressure                |
+-----------------------------+--------------+-------------------------+
| Dec 1989 to Mar 1990        | No data      | No data                 |
+-----------------------------+--------------+-------------------------+
| Apr 1990 to May 1990        | 3401-a1h     | 3401-a1h                |
+-----------------------------+--------------+-------------------------+
| Jun 90                      | No data      | No data                 |
+-----------------------------+--------------+-------------------------+
| Jul 1990 to Aug 1990        | 3471-a1h     | 3471-a1h                |
+-----------------------------+--------------+-------------------------+
| Sep 1990                    | No data      | No data                 |
+-----------------------------+--------------+-------------------------+
| Oct 1990 to Feb 1991        | 3581-a1h     | 3581-a1h                |
+-----------------------------+--------------+-------------------------+
| Feb 1991to Mar 1991         | 3741p-a1h    | 3741p-a1h               |
+-----------------------------+--------------+-------------------------+
| Apr 1991 to May 1991        | No data      | No data                 |
+-----------------------------+--------------+-------------------------+
| Jun 1991 to Oct 1991        | 3831-a1h     | 3831-a1h                |
+-----------------------------+--------------+-------------------------+
| Oct 1991 to Feb 1992        | 3891p-m1h    | 3891p-m1h               |
+-----------------------------+--------------+-------------------------+
| Mar 1992 to May 1992        | No data      | No data                 |
+-----------------------------+--------------+-------------------------+
| Jun 92 to Sep 1992          | 4001p-a1h    | 4001p-a1h               |
+-----------------------------+--------------+-------------------------+
| Oct 1992 to Feb 1993        | 4071p-a1h    | 4071p-a1h               |
+-----------------------------+--------------+-------------------------+
| Feb 93 to Jun 1993          | 4131p-a1h    | 4131p-a1h               |
+-----------------------------+--------------+-------------------------+
| Jun 1993 to Oct 1993        | 4201p-a1h    | 4201p-a1h               |
+-----------------------------+--------------+-------------------------+
| Oct 1993 to Feb 1994        | 4281p-a1h    | 4281p-a1h               |
+-----------------------------+--------------+-------------------------+
| Feb 1994 to Jun 1994        | 4301p-a1h_d1 | 4301p-a1h_d1            |
+-----------------------------+--------------+-------------------------+
| Jun 1994 to Oct 1994        | 4401p-a1h    | 4401p-a1h               |
+-----------------------------+--------------+-------------------------+
| Oct 1994 to Feb 1995        | 4451p-a1h    | 4451p-a1h               |
+-----------------------------+--------------+-------------------------+
| Feb 1995 to Jun 1995        | 4501p-a1h    | 4501p-a1h               |
+-----------------------------+--------------+-------------------------+
| Jun 1995 to Sep 1995        | 4601p-a1h    | 4601p-a1h               |
+-----------------------------+--------------+-------------------------+
| Sep 1995 to Jan 1996        | 4621p-a1h    | 4621p-a1h               |
+-----------------------------+--------------+-------------------------+
| Feb 1996 to Jun 1996        | 4651p-a1h    | 4651p-a1h               |
+-----------------------------+--------------+-------------------------+
| Jun 1996 to Oct 1996        | 4701p-a1h_d1 | 4701p-a1h_d1            |
+-----------------------------+--------------+-------------------------+
| Oct 1996 to Feb 1997        | 4801p-a1h_d1 | 4801p-a1h_d1            |
+-----------------------------+--------------+-------------------------+
| Feb 1997 to Jun 1997        | 4951p-a1h_d1 | 4951p-a1h_d1            |
+-----------------------------+--------------+-------------------------+
| Jun 1997 to Sep 1997        | 5011p-a1h_d1 | 5011p-a1h_d1            |
+-----------------------------+--------------+-------------------------+
| Sep 1997 to Jan 1998        | 5071p-a1h_d1 | 5071p-a1h_d1            |
+-----------------------------+--------------+-------------------------+
| Feb 1998 to Jun 1998        | 5161tcp-a1h  | 5161var-a1h_d1          |
+-----------------------------+--------------+-------------------------+
| Jun 1998 to Sep 1998        | 5301Atcp-a1h | 5301Avar-a1h_d1         |
+-----------------------------+--------------+-------------------------+
| Sep 1998                    | 5301Bp-a1h   | 5301Bvar-a1h_d1         |
+-----------------------------+--------------+-------------------------+
| Oct 1998 to Feb 1999        | 5401tcp-a1h  | 5401var-a1h_d1          |
+-----------------------------+--------------+-------------------------+
| Feb 1999 to May 1999        | 5521tcp-a1h  | 5521var-a1h_d1          |
+-----------------------------+--------------+-------------------------+
| May 1999 to Jun 1999        | 5692Atcp-a1h | 5692Avar-a1h_d1         |
+-----------------------------+--------------+-------------------------+
| Jun 1999 to Sep 1999        | 5692Btcp-a1h | 5692Bpsd-a1h            |
+-----------------------------+--------------+-------------------------+
| Sep 1999 to Jan 2000        | 5912p-a1h    | 5912var-a1h_d2          |
|                             |              |                         |
|                             |              | 5912psd-a1h             |
+-----------------------------+--------------+-------------------------+
| Feb 2000 to May 2000        | 6112tp-a1h   | 6112psd-a1h             |
+-----------------------------+--------------+-------------------------+
| May 2000 to Sep 2000        | 6252p-a1h    | 6252var-a1h             |
|                             |              |                         |
|                             |              | 6252psd-a1h             |
+-----------------------------+--------------+-------------------------+