Superman (1978), Batman (1989), and Spider-Man (2002) each broke box-office weekend records. Adjusting for inflation, theater counts or population growth may mitigate the impressive intakes of other comic book blockbusters, but not those three. Today The Dark Knight has set a new mark for weekend ticket sales, putting it in deceptively good position to join the pantheon.
Top 25 Comic Book Movies by Tickets Sold
Batman's 10.2-million-tickets opening bested previous record-holder 1984's Temple of Doom by nearly 50%. Yet, while one in every 24 Americans saw Batman on its opening weekend, one in every 13.5 saw The Dark Knight.
≈96% as many people saw The Dark Knight this weekend as saw 1997's Batman & Robin in its entire run (23.4 mil). Previous record-holder Spider-Man 3's opening run represented a whopping 45% of its total; similar attrition for The Dark Knight would bring in 51 million tickets, surpassing ...Begins (32 mil), ...Returns (39 mil), and ...Forever (42 mil) to become the 2nd most-seen Batman movie.
Catching the original Batman would require the sale of 38 million more tickets. 47 million more would match Spider-Man's 69-million-mark, which is the 2nd-highest this decade, but — as Shrek 2 proved — doable even for a sequel. To match Superman's being seen by one-in-every-3.88 Americans, however, The Dark Knight would have to sell 56 million more. At today's prices, that would be a haul of $540 million, smack dab between Star Wars: A New Hope and Titanic.
Box office data -- http://boxofficemojo.com/genres/chart/?id=comicbookadaptation.htm
Monthly Population 1978-1999 -- http://www.census.gov/popest/archives/1990s/nat-total.txt
Monthly Population 2000-2007 -- http://www.census.gov/popest/national/NA-EST2007-01.html
July 2008 Population -- http://www.census.gov/main/www/popclock.html
 Coincidentally Ghostbuster II set the box office revenue record in the prior week and Returns would end up breaking it yet again.
 Box office numbers we see include Canada, so this ratio is ntrinsically flawed. Of course, the ticket sales themselves are just estimates and can't account for such variables as discounted prices (eg children) per picture. This is all just an excuse to post a pretty chart, though. p_^