At what ages do children stop believing in Santa Claus?

Research in the Journal of Cognition and Development in 2011 shows that 83% of 5-year-olds think that Santa Claus is real, the study’s lead author, Jacqueline Woolley, wrote in The Conversation last year.

“We have found in more recent studies that that number of 85% sounds about right,” said Thalia Goldstein, assistant professor of applied developmental psychology at George Mason University in Fairfax, Virginia.

“Children’s belief in Santa starts when they’re between 3 and 4 years old. It’s very strong when they’re between about 4 and 8,” she said. “Then, at 8 years old is when we start to see the drop-off in belief, when children start to understand the reality of Santa Claus.”

What about across the pond?  They seem to be asleep over there:

Of 161 parents in the United Kingdom, 92.5% thought Father Christmas was real for their children up to the age of 8, according to a research paper presented at the annual meeting of the European Early Childhood Education Research Association in Finland in 1999.

And here is a study vulnerable to the replication crisis:

The interviews revealed that 39.2% of the children believed that the man they visited was the same Santa who came down their chimneys…1.3% had a somewhat “adult belief,” Goldstein said, in which they said that the man was not Santa and did not live at the North Pole but could communicate with the real Santa.

That is a CNN article from last year.  Why is the word “marginal” declining in popularity?  How many seven year olds know what “marginal” means?  How many know not to believe everything the President says?  How many understand hedging?