Compressed Backup too big

"PostgreSQL 8.2.3 on i686-pc-mingw32, compiled by GCC gcc.exe (GCC) 3.4.2
(mingw-special)"
Database size in disk returned by pg_database_size() is 210 MB

Database compressesed backup file size is now 125 MB.
This seems too much. I expect compression to decrease size 10 times, also
indexes are not backed up. A year ago compressed backup size was 9 MB only.

I created query returning biggest tables with and without indexes and found:

1 pg_toast_22185 95 MB 96 MB
2 rid 21 MB 27 MB
3 klient 13 MB 19 MB
4 mailbox 10 MB 11 MB
5 dok 7640 kB 12 MB
6 desktop 8080 kB 8200 kB
7 strings 5536 kB 6584 kB
8 pg_toast_22338 5232 kB 5368 kB

...

Questions:

1. Tables are relatively small and thus cannot create 125 MB compressed
backup file.
Why backup file sis so big ?

2. How to determine what data is containing in pg_toast_22185 ?
Why this is so big ?

Andrus.