it increases exponentially as it reaches and passes $3/gal. when $4 is "achieved", half the posts are either spam or talk of fuel saving devices/additives.
Sad but true... I also started banning IP addresses of repeat spammers last week. Once the same IP spams us twice, it will be banned, and then you won't even be able to view the site from that IP. After we have a decent banlist the influx of spam will decrease.