How to aggregate/Sum multiple CPU cores to get one CPU metric in grafana?

Is there a way to aggregate across metrics/metric-names? For example, on a four core system, you have the following metric-names:

cpu.0.system cpu.1.system cpu.2.system cpu.3.system

I would like to SUM(cpu.*.system) to get the aggregated cpu.system.total.

Is there a way to accomplish this with the current Grafana-graphite query-editor?

Please advise.

I got one other solution as described below:

Edited vi /opt/collectd/etc/collectd.conf file.

Uncomment LoadPlugin aggregation.

LoadPlugin aggregation
<Plugin aggregation>
  <Aggregation>
    #Host "unspecified"
    Plugin "cpu"
    #PluginInstance "unspecified"
    Type "cpu"
    #TypeInstance "unspecified"

    GroupBy "Host"
    GroupBy "TypeInstance"

#    CalculateNum false
#    CalculateSum false
    CalculateAverage true
#    CalculateMinimum false
#    CalculateMaximum false
#    CalculateStddev false
  </Aggregation>
</Plugin>

And restarted the collecd services.