Hello Jurgen,
The data you whant are on an exterior database, or are on QOS format?
If they are on a database, it will be necessary that database schema to provide you a query.
If they are on QOS format you can do that on dashboard without a SQL Query.
First on datasource selection chose advanced datasource
Then select QOS and create a new one:
then chose the interface QOS, it may be something like QOS_INTERFACE_BITSIN
Create and associate that to the graph, and go to the Serie configuration and select the Serie
Finaly configure the multiplier and you gonna have the result you whant