The good news: Disney’s Rogue One: A Star Wars Story is an enormous hit, with about $155 million in domestic ticket sales for its opening weekend. That will likely propel the year’s box-office sales, as our Anthony D’Alessandro points out, to an $11 billion-plus record.

Less good: Even big movies like this year’s Star Wars entry are working harder to make an impression on the growing North American audience.

Or think of it this way. Movies swim in an ever-larger pool of potential ticket-buyers. So each year, a film must swallow a slightly higher number of sales to match the share consumed by comparable predecessors.

Occasionally, a film breaks out and becomes an audience-eating monster. In 2015, for instance, Disney’s Star Wars: The Force Awakens sold about 28.5 million tickets in the North American market, to set an opening weekend record, according to charts compiled by Boxofficemojo.com. That means about 8 percent of the combined U. S.-Canada population, then roughly 358 million, saw the movie when it opened. Rogue One: A Star Wars Story, by comparison, sold about 18.2 million tickets in the same market, which is probably over 360 million people this year. So the new film was seen by around 5.1 percent of the viewers, a share that is about 36 percent lower than that of its predecessor.

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That Rogue One is smaller than The Force Awakens isn’t news. Disney has spent the better part of a year dousing any expectation that the spin-off would match the parent.

But audience share calculations get more interesting when you reach back a decade or two, to look at the performance of blockbusters past. In terms of opening weekend-ticket sales, for instance, Rogue One clearly edged DreamWorks Animation’s Shrek 2, which had 17.4 million domestic ticket sales when it opened in 2004. In the Boxofficemojo ranking, Rogue One ranked 17th, while Shrek 2 placed 21st in terms of opening weekend tickets sold. But Shrek 2 reached about 5.4 percent of a smaller population; so it loomed a little larger for the audience.

In 2006, Disney reached about 6.3 percent of the North American population with Pirates of the Caribbean: Dead Man’s Chest, which had about 20.7 million in opening weekend ticket sales. The film’s share was almost 24 percent higher than that of Rogue One. Similar is the gap between Rogue One and Sony’s Spider-Man, which had about 19.8 million ticket sales when it opened in 2002. That represented around 6 percent of the combined population, a share 18 percent higher than was posted by Rogue One this weekend.

Other films that reached a higher percentage of the population than Rogue One on opening weekend included The Twilight Saga: New Moon, Shrek The Third, and The Lost World: Jurassic Park, all of which had lower dollar receipts at the box-office when they opened.