I would like to know the number of people who saw the movie "Moulin
Rouge" in the United States and worldwide (separate numbers).  I
suppose this should include (a) the number of people who saw the movie
in theatres and (b) the number of people who rented to the movie
(Blockbuster, etc.) -- although I'd settle for just the movie-goers as
a definitive number.  Would like the source of data to be credible/defendable

The Rotten tomatoes site gives total money taken in theatre and VHS in
the US, but not numbers
http://www.rottentomatoes.com/m/MoulinRouge-1107863/numbers.php

and "The Numbers" site gives weekly breakdowns....
http://www.the-numbers.com/movies/2001/MOULR.html

Not what you want I know, but interesting........

Willie-ga

Business Data for Moulin Rouge! (2001) 
Because movie theaters don't track indiviuals (yet), it is difficult
to know how many people saw it versus the number of admissions (some
may see it more than once).  Even more difficult if you include repeat
viewings via rentals (also pay-per-view, premium movie channel,
purchase,...).

http://lumiere.obs.coe.int/web/EN/film_stats.php?film_id=17259
For admissions, US: 10 583 473, Europe (35 countries?): 11 994 955 

http://www.imdb.com/title/tt0203009/business

www.obs.coe.int/online_publication/expert/musicals.ppt
ADMISSIONS TO MUSICAL FILMS  
(US/CA + EUROPE) (1996-2002) 
in millions 
Source : European Audiovisual Observatory / LUMIERE 
          EUR  US/CA  EUR+US/CA
MOULIN ROUGE 11,5  10,5  22,1