Grafana: Show median request time as value (using @Timed from micrometer)

Question

i've using the @Timed Annotation in my SpringBoot Application:

@Timed(value = "stats.myapp.dosomething")
public void doSomething() { ... }

Now I would like to display the average/median processing time in Grafana. So i've used a Stat widget with the following query:

SELECT mean("sum") FROM "stats.myapp.dosomething" WHERE time >= now() - 2d and time <= now() GROUP BY time(2m) fill(none)

But the value still shows 0 :(

I suspect it has to do with all the 0 values. How can I suppress them?

Thank you!