What does "average" mean in Grafana legends?

I have data in InfluxDB for power (watts) that is irregularly spaced in time. I only push data into InfluxDB if there’s been a big enough change. As a result, I’m concern about the “average” legend value in Grafana. Is this a time average or is it summing the points and dividing by the number of points?

For example, say the first 30 seconds of data fluctuates between 45 watts and 55 watts and there are lots of data points, while the next 30 seconds is 0 all the way through so I only get a single data point of 0. The time average should be 25W for that minute. But if you average by number of data points, the n-average would be closer to 50W for that same minute.

If the legend average is a n-average instead of time average, is there a way to get Grafana to report out time average for non-reguarly spaced data?