When I compile the data for the attendance, I do it on a 1 through 41 game basis for all 30 teams. I find that makes it easier to compare the numbers from seasons past, especially when calculating per-game averages.
For example, to say that the Grizzlies are averaging 12,096 per game is meaningless when you compare it to their overall average from past seasons, because attendance clearly rises as the season progresses. By tracking the attendance on a game-by-game basis, I can compare Memphis' numbers from their first four games of this season to past seasons (which, if you're interested is 11,924 last year and 14,514 from the year before).
Anyhow, after I get the numbers for the individual teams, I like to total up game one, game two, etc., just to see how the league is doing after "Game 1" and so forth. It's not completely infallible - after all, game 7 in one season might have alot of Saturday night games, while game 7 in another season had alot of Tuesdays, but these things average out over the course of the season (I hope).
With that in mind, if you're still following along, that is, and with Denver hosting a game last night, all 30 teams have now played a minimum of four home games. Combined with the 41 games from each of the two previous seasons, that makes 86 games for which I have data on per-game attendance.
Care to take a guess where nights 2, 3 and 4 rank out 86?
Game 2: #86
Game 3: #80
Game 4: #85
All of which is a very long-winded way of saying that so far this season the NBA has managed to post the Worst, Second-Worst, and Sixth-Worst attendance figures of the past three seasons - and we're just getting started.