Adding a weighted % Complete

Is it possible to create a weighted % complete column in MSP?

I have to put a weighted % against different disciplines within the schedule however I'm not really sure where to start. 

So I have for example:

Engineering 10%

Procurement 10%

Structural 25% 

And so on. 

I was thinking I would need to create a text column indicating which discipline each activity comes under and then do a sumif on the durations? 

Any help would be appreciated

Thanks