Using Aggregate Count with variable Time Range?

So I have a query that pulls data into Grafana like so:

  count(id) AS "Generated Count"
FROM transaction
ORDER BY $__timeGroup(txTimestamp,$__interval,NULL)

But it means that the Y-Axis of my graph isn’t static, it changes depending how zoomed in/out the graph is. So sometimes the count is per second (rows/sec), othertimes it can be per 10 secs.

I don’t mind this behaviour, but I’d really like to display the value of a “time-slice” on the graph somewhere, so that if someone is comparing two different graphs, they can get back to the “per sec” values and compare like-for-like.

That, or make it so the Y axis is always per second?