The top 10 trending keywords registered in .COM and .NET domain names during the month of January 2019 were published by Verisign, the .com and .net registry.
You can find the list from last month here.
My experience shows that 700 or 800 (or even less) domain registrations are enough to bring a keyword into the top 10.
There was on common keyword in the 2 lists: keto.
I had to google what keto is. It turns out a keto or ketogenic diet is a very low-carb diet, which can supposedly help you burn fat more effectively. It seems to me it is somehow dangerous if not done properly or without your doctor approving it. But again all diets need to be done correctly.
The 2 lists also have a lot of legal keywords.