Num MsgsNumber of messages sent to the list by the contributor during the period
% MsgsThe percent of list messages sent by the contributor
Num LinesNumber of lines in message bodies contributed by the contributer during the period
% Quoted LinesOf the contributor's message lines, this percentage appear to be quotations from other messages
Avg SizeAverage body size of the contributor's messages, in bytes
ZedThis approximates the contributor's number of messages per day, based on a standard 30-day month
QueThis is a measure of the contributor's overall amplitude on the list during the reporting period
UserThe contributor's address, slightly obfuscated

Past statistics by month are occasionally posted HERE.