Add dollar amount of earnings per gig to analytics page

[misscrystal]

I would like to see how much each gig has earned for each 7 days, 30 days, 3 months and 6 months.

Since I have raised my gig prices, my earnings have climbed over time. Simply seeing how many orders I have per gig does not give an accurate picture of the performance of my gigs.

Number of orders can decline by half at the same time earnings per gig have increased four times over.