Seconds, yes. Sorry I figured that was obvious, I'll add it to the graphs I generate next week.
https://handsondataviz.org/images/14-detect/gdp-baseline-mer...
And what is going on with that Y axis? There is no consistent spacing between the marks!
Seconds was my best guess .. but that doesn't make it certain for the viewer.
No real drama, but FWiW I've looked at a lot of data across engineering, math, geophysics, mining, energy, etc and unlabeled data and graphs are a major annoyance.