Calculating data growth for mutiple servers


I’m using Grafana to visualize performance and capacity informations of Hitachi Storage Systems.
The data is stored in a graphite backend and accessed from grafana using graphite-api.

I need to create a dashboard that contains a table that shows the data growth of all servers connected to a storage system. If I query the current capacity for all Oracle servers the query looks like:

So now I have the current data and I need to “compare” it to the data 180 days ago to see the growth of the last 180 days.

I get managed to do this for one server:

So you can see that the capacity was decreasing by approx. 30% over the last year.
If I change to the Hostname “OracleDB#####10” to Oracle* the query won’t work since asPercent only accepts a single Series but not many series…

I tried to work with map and reduceSeries but it looks to me this is only working in one query but due to the timeshift I will need 2 queries.

Does anyone has an idea how I could solve that issue?
Thanks in advance for any comments and feedback.