title: Create sum of multiple queries with influxdb
body: <p>I have four singlestat panels which show my used space on different hosts (every host has also different type_instances):</p>
  <p><a href="https://i.stack.imgur.com/Wipe0.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Wipe0.png" alt="enter image description here" /></a></p>
  <p>The query for one of this singlestats is the following:
  <a href="https://i.stack.imgur.com/ibCVz.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ibCVz.png" alt="enter image description here" /></a></p>
  <p><strong>Question:</strong> Is there a way to create a fifth singlestat panel which sows the sum of the other 4 singlestats ? (The sum of all &quot;storj_value&quot; where type=shared)</p>