Show bytes sent the last days, weeks, month

1

I would like to have a short table in Grafana which shows me the total number of Bytes sent/received on an interface. The issue I currently face is that the bytes_sent (or bytes_received) number is jumping, i.e. falling back once the max. number is reached. See attached screenshot to show what I mean:

grafik

My question is how to calculate/query the number of bytes sent the last day, week, current and previous month.

2

Is it really not possible to get the number of Bytes send over the last, say n days or so - I though this is quite some basic stuff and should be easy to get. The number is sometimes important for connections with accounting (i.e. max. volume limits). Any idea, hint or comment is really more than welcome!