HTTP Request Throttle, how to log?

I am using a slightly modded version of the HTTP Request Throttle irule found on http://devcentral.f5.com/wiki/default.aspx/iRules/HTTPRequestThrottle.html:

when RULE_INIT {
set static::maxRate 60
set static::windowSecs 30
set static::timeout 60
set static::log_interval_vip1 2
set static::redirect_url_vip1 "http://some.site.com"
}

when HTTP_REQUEST {
    set myUserID "user"
    set currentTime [clock seconds]
    set windowStart [expr {$currentTime - $static::windowSecs}]
    set postCount 0
set timeTable "TS-limited_uri"
set key "ST-limited_uri"
table add -subtable $timeTable $key [clock seconds] indef indef
set log_timestamp [table lookup -subtable $timeTable $key]
    foreach { requestTime  } [table keys -subtable "PH:${myUserID}"] {
        if { $requestTime > $windowStart } {
            incr postCount 1
        } else {
            table delete -subtable "PH:${myUserID}" $requestTime
        }
    }

if {[expr {$currentTime - $log_timestamp}] > $static::log_interval_vip1 } {
table set -subtable $timeTable $key [clock seconds] indef indef
log -noname  local0. "Rate: ($postCount) !!!"
}

if { $postCount < $static::maxRate } {
        set requestID "PH:${myUserID}"
table set -subtable $requestID $currentTime "ignored" $static::timeout 
} else {
            HTTP::redirect $static::redirect_url_vip1
            return
        }
}

The irule works a treat and I have tried introducing some logging that would give an indication of the rate of reqs/s but when I log the value of postCount it will keep rising until it its the vales set for static::windowSecs. i.e

set static::windowSecs 30 == local/tmm info tmm[18771]: Rate: (29)

set static::windowSecs 60 == local/tmm info tmm[18771]: Rate: (59)

Any suggestions on how to do this properly?

Cheers,

Claud