Over Memorial Day weekend this year, Disney’s Alice Through the Looking Glass opened to an abysmal $33 million over the holiday weekend, immediately making it one of the biggest bombs of 2016. How poor was that opening? It’s the sequel to 2010’s Alice in Wonderland, which made $116 million in its first weekend (which was a three-day frame, not a four-day one). Looking Glass will be lucky to make $80M in its entire domestic run, nearly $40M under what Wonderland earned in its premiere weekend. Ouch.

Is there an easy explanation? Did Disney take too long with the six year hiatus between franchise entries? Perhaps. Did the negative tabloid publicity surrounding star Johnny Depp hurt? Maybe.

Yet another explanation is likely part of the equation. In 2016, moviegoers have seemed to catch a case of “sequelitis” and their symptoms have been affecting box office grosses for a number of pictures already this year.

Over that same Memorial Day weekend, X-Men: Apocalypse ruled the charts with a $79 million debut. That would seem impressive, except X-Men: Days of Future Past made $110 million over the same weekend just two years earlier.

This story has repeated itself repeatedly in recent months. Ride Along 2 was expected to build on its predecessor’s opening weekend. The 2014 original cruised to a $41M opening. The sequel: $35M. When all was said and done, the first Ride made $44M more than its follow-up.

Other comedies have suffered the same fate. 2001’s Zoolander actually only made $45 million in its initial run, but became a major cult hit in subsequent years. It’s long gestating sequel would surely earn more. It didn’t. Just $28M.

2002’s My Big Fat Greek Wedding became the unexpected smash of that year with $241M stateside. Part 2? $59 million (to be fair, this was on the higher end of many expectations, but still just 25% of what the first Wedding did).

2014’s Neighbors? $150 million. Last month’s Neighbors: Sorority Rising? It should top out at around $60M.

Barbershop: The Next Cut will make $55 million, under the $75M and $65M of its predecessors (though still not bad).

The action crowd has showed their ambivalence. London Has Fallen earned a just OK $62 million compared to Olympus Has Fallen‘s $98M.

2014’s Divergent made $150 million. 2015’s Insurgent: $130 million. This year’s Allegiant: a troubling $66 million.

Then there’s The Huntsman Winter’s War, which may not even reach $50 million. It’s the sequel to Snow White and the Huntsman, which made $155 million.

Just this weekend, Teenage Mutant Ninja Turtles: Out of the Shadows took in $35 million in its debut, which is a shell of the $65 million that the first made two summers ago.

Faith based audiences propelled God’s Not Dead to a heavenly $60 million gross in 2014. Part 2? $20 million.

Kung Fu Panda 3 performed decently with $143 million, but couldn’t match part 1’s $215M or part 2’s $165M.

Seeing a trend here, folks?

There have been rare exceptions in 2016 so far. 10 Cloverfield Lane managed $72 million. Even though that’s below the $80M of Cloverfield, it’s still a solid gross and a profitable venture for its studio.

And Captain America: Civil War was widely expected to outdo the respective $176M and $259M earnings of the first two entries. This was due to it basically being The Avengers 3. It did and will top $400M domestically.

Coming this weekend: two more sequels will try to avoid the 2016 trend and both actually have a decent chance of succeeding. The Conjuring 2 is receiving positive reviews and its studio is hoping the goodwill left over from the 2013 original will propel it to similar grosses (I’m predicting it’ll make $42 million for its start, slightly above the first).

Now You See Me 2 is hoping to match the $29 million made by the 2013 original for its beginning. I’m predicting $24M.

If both of these titles come in below expectations, that may truly show that crowds are just plain sick and tired of seeing roman numerals and numbers behind titles. Looking over the remainder of the 2016 calendar, there’s a heap of sequels that could also struggle to match what came before them. They include:

The Purge: Election Year. Bridget Jones’s Baby. Underworld: Blood Wars. Jack Reacher: Never Go Back. Ouija 2. Bad Santa 2.

Even this month’s Independence Day: Resurgence is an iffy proposition to capitalize on the nostalgia factor from the 1996 original. It appears unlikely to match the $306M earned 20 years ago by the first one.

Next month’s Star Trek Beyond could have trouble matching the $228M made by part 2 in 2013.

Inferno, the third Tom Hanks thriller based on Dan Brown’s novels, is a question mark to match the $133M that Angels & Demons made in 2011 and certainly won’t approach The Da Vinci Code‘s $217M a decade ago.

When it comes to 2016 sequels, it might not all be bad news. Finding Dory (out June 17) shouldn’t have much trouble topping the $70M that Nemo made in 2003 (though whether it reaches its eventual gross of $380M is a mystery).

And July’s Jason Bourne should benefit from having Matt Damon return to the franchise after nine years away. It should manage to outpace the $113M made by Jeremy Renner’s The Bourne Legacy in 2012. However, could it approach the $227M earned by Damon’s last one, 2007’s The Bourne Ultimatum? Probably not.

Perhaps these disappointing results for so many sequels will cause studios to give us more original programming, but don’t hold your breath. Next year is already packed with follow-ups and some of them already look like they could be in trouble.

For instance, it’s probably safe to assume Disney is sweating over the fifth Pirates of the Caribbean flick, Dead Men Tell No Tales. Same goes for Lionsgate with their final Divergent pic, Ascendant.

Some of the 2017 sequels that may not have much to worry about: Guardians of the Galaxy Vol. 2. Fast 8. And, of course, Star Wars: Episode VIII.

Yet given the recent trends, who knows? No one thought Alice or Huntsman or Allegiant would do that poorly and it’s contributed to a bad… and maybe badly needed downturn for sequels in 2016.