When I do a gstat on my database with user name and password I get the
following. Now this probably is very informative and can probably tell me
how efficient my indexes are or not. Just I have no clue how to interpret
this information is there and article or a pdf file I could look into which
actually explains the reading of this info ?

CITY (129)
Primary pointer page: 147, Index root page: 148
Data pages: 62, data page slots: 67, average fill: 70%
Fill distribution:
0 - 19% = 8
20 - 39% = 13
40 - 59% = 1
60 - 79% = 0
80 - 99% = 40

Index RDB$5 (1)
Depth: 2, leaf buckets: 14, nodes: 3049
Average data length: 12.00, total dup: 0, max dup: 0
Fill distribution:
0 - 19% = 0
20 - 39% = 0
40 - 59% = 0
60 - 79% = 0
80 - 99% = 14

COUNTRY (128)
Primary pointer page: 145, Index root page: 146
Data pages: 4, data page slots: 4, average fill: 90%
Fill distribution:
0 - 19% = 0
20 - 39% = 0
40 - 59% = 0
60 - 79% = 1
80 - 99% = 3

Index RDB$2 (1)
Depth: 1, leaf buckets: 1, nodes: 237
Average data length: 7.00, total dup: 0, max dup: 0
Fill distribution:
0 - 19% = 0
20 - 39% = 0
40 - 59% = 0
60 - 79% = 0
80 - 99% = 1