With a tool like Nudge, you can see the overall site average scroll on the Insights tab. You can then go to the Content tab, to go into each URL and see it was for any particular page.
You can also slice that by device & date range, to see performance at a more granular level.
If you need to diagnose scroll performance, there is an analysis highlighting where people drop off, and overlaying attention and scroll. To find areas that people skip, or dwell on.