How Often Are Detections

I know last detection was July 2017 but is there one predicted in the near future, and how spread out are the detections 1-2 years 2-3 years ect.

When CS:GO is on sale, that is usually when they decide to do a VAC wave. However, they have been sleeping for many sales and hit no one.

We can't predict the next time we'll get hit and we have no reason to believe we'll be hit in the near future.
Detections are usually spread out from half a year to a year.