Structurally, the movie box office is pointed back to the future, but with a couple of twists.

As we approached mid-July, according to data compiled by Boxofficemojo.com, the domestic box-office take for films released in 2018 was startlingly top-heavy. According to numbers posted Friday—before the current weekend is factored in—the Top Ten films, led by Black Panther, accounted for $3.34 billion, or 58.8 percent, of the $5.68 billion in sales for 362 movies. So 352 films were left to split $2.34 billion, for an average of about $6.6 million each (though a great deal of that went to the Second Ten, leaving crumbs for the rest).

In the year’s second half, of course, performance will even out a bit, as awards contenders and holiday films diminish the lead by first-half blockbusters. But it appears likely that, for the first time in recent memory, the Top Ten films will finish the year with 40 percent or more of the total box-office. Several of the biggest movies, including Jurassic World 2 and Incredibles 2, are still selling tickets. At the same time, several current Top Ten movies have taken in less than $200 million, a situation that will change by year’s end, when fresh blockbusters—Dr. Seuss’ The Grinch? Spider-Man: Into The Spiderverse?—will push every movie in the top rank above the $200 million mark, as has happened each year since 2011.

Top-loading of the box-office is a clear trend. For the last three years, at least a third of domestic tickets sales have gone to the first ten movies. In the prior 17 years, the figure was generally closer to 25 percent, and fell as low as 22.2 percent in 2000, according to Boxofficemojo data. In that year, How The Grinch Stole Christmas led the pack with about $260 million, but the top films accounted for only $1.72 billion of the $7.74 billion taken in by 374 releases.

So the big are getting bigger. The middle is shrinking. And almost everybody in the film business knows it. But what’s surprising—at least to me—is that the pattern has precedent.

In the early 1980s, in fact, box-office top-loading was even more extreme than it has yet become today. In 1984, when Beverly Hills Cop was the big hit, the Top Ten films accounted for $1.27 billion of $3.35 billion in sales for the films released that year or 37.9 percent. That’s a bit higher than the recent high of 36.1 percent, achieved in 2015, when Star Wars: The Force Awakens dominated sales.

In 1982, the Top Ten, led by E. T.: The Extraterrestrial, eventually accounted for 43.9 percent, or $1.26 billion, of $2.87 billion in sales for all the year’s releases.

Thus, top-loading isn’t entirely new. But the current trend is marked by two changes that will affect industry decisions for years to come.

First, as veteran film consultant David Gross has pointed out in a survey introducing his new Franchise Entertainment Research company, the gap between performance by franchise films like the Marvel movies and one-offs like American Sniper or Gravity has widened. “Non-franchise B.O. fell in 2017 to its lowest level ever,” Gross wrote.

Second, the total number of releases has grown sharply, even as ticket sales cluster at the top. Boxofficemojo.com tracked 738 films last year, up from 132 back in 1982, when sales were similarly top-heavy.

Through the intervening decades, a steadily growing flow of movies from independent and quasi-independent companies helped to spread sales through the Top Hundred. Now, almost all but the first ten movies will survive through digital and foreign sales, or not at all.