Sales Performance of Exhibitions Comparison Widget

Hi,

I'd like to do a comparison of two separate exhibition's sales, ideally using a line chart in Analytics. Something like the Running Sales Total by Order Week Widget except i want to compare exhibitions that occurred in different years.

I'd like to compare sales performance of last year's Magritte exhibit to sales performance of this year's Warhol exhibit over the course of time that tickets went on sale through to the exhibition closing for each.

Any tips would be greatly appreciated. 

Thanks!