Auto vacuum configuration in postgres.

Hi All,
       In my application we are using postgres which runs on an
embedded box. I have configured autovacuum to run once for every one
hour. It has 5 different databases in it. When I saw the log messages,
I found that it is running autovacuum on one database every hour. As a
result, on my database autovacuum is run once in 5 hours. Is that an
expected behavior, Is there any way to make it run it every hour.


Thank you,
Venu