Get/v3/events state:new

I was wondering what classes as new?
I want to get events but not miss any of the ones I want so was trying to work out how to only get ones that have appeared sinc eI last checked.

For me it seems to never show anything.
How can I check for markets that have been recently added?
I tried using last_modified_min but that just shows any market that has changed in any way.