webalizer - how to store 24 months instead of just 12

[MediaHound]

Webalizer keeps track of the last 12 months' data.
Hence:
`Summary Period: Last 12 Months`

How could I safely change this to chart 24 or 36 months' history?

I searched and couldn't find it with the keywords I was using.
If it was brought up before, please steer me in the right direction.

Thanks

[ng_kiangkai]

I also have similar problem like u. Do you know how to display summary period for every months in webalizer in one page. It will store in Cpanel, but i cannot see previous summary report. Is anyone have idea to do that?