I think changes to phrases that don't change their meaning are interesting. Example: an ice cold beer and a nice cold beer mean pretty much the same thing.
I heard another one this morning on the radio in a story about coal. The phrase used is fluctuates widely, but I know I've also heard fluctuates wildly. Looking at the ngram, I'm surprised to see that "widely" is far more popular (although with 0 smoothing, it does fluctuate wildly ;-).
Any idea where either of these phrases comes from, which came first, and/or which is more correct? wildly makes more sense to me in most contexts, but widely makes sense too.
Best Answer
Andrew Neely is close, but not quite there:
"Fluctuates widely" means the standard deviation (possible ranges, whatever) is (relatively) huge.
"Fluctuates wildly" means the standard deviation isn't necessarily huge, but it wavers between its two extremes very often.
What you have is a punnet square of possibilities: Not widely and not wildly, just widely, just wildly, and both widely and wildly. Choosing whether to use "widely" or "wildly" in speech depends first on whether both apply, and then on which one you want to draw attention to.
EDIT: Jefromi brings up a good point in the comments, that while "wildly" doesn't mean "widely", it's not often used for small, rapid fluctuations. So I'll include a third option that embodies that description: "fluctuates rapidly".