Agchristie....I have no idea of the numbers involved, although the very first Aussie edition, published in 1963 caused a sensation, selling 6,000 copies by lunchtime of publication day.
But you can read the entire series, both Aussie and British on-line these days here ::::
http://ro.uow.edu.au/ozlondon/
Oz was revolutionary for its time. It challenged bigotry in a way that hadn't been done before. To quote from the Wiki entry ::
"In succeeding issues (and in its later London version) OZ gave pioneering coverage to contentious issues such as censorship, homosexuality, police brutality, the Australian government's White Australia Policy and Australia's involvement in the Vietnam War, as well as regularly satirising public figures, up to and including Australian Prime Minister Robert Menzies"
Its important to realise that nobody has really questioned those issues before Oz came along. Its also important to remember that Australia played a military part in the Vietnam War, something that was urged of Britain by he US President, but which Macmillan declined.