127.0.0.1 - - [24/Jun/2007:12:05:36 -0400] "GET /~chewie/webtop/" 200 660 "-" "-"
127.0.0.1 - - [24/Jun/2007:12:05:43 -0400] "GET /~chewie/webtop/" 200 - "-" "-"

The 660 is %b, the amount returned to client.