I've been thinking about this concept for a long time, as I've had a couple decades of experience as a performing musician. Now I've put together a subscribable calendar which gives performers access to the predicted value of a date. I validated this calendar against my own sbusy performance Schedule for the last 15 years, and I think it will be a valuable tool for any experienced performer who understands that certain dates have more value than others.
The way I use it is when I get a call for a certain date. I'll have a look at that date in my calendar and see how high value it is so that I know whether I should expect to get more calls on that date or not. This calendar will give anybody a handy reference. You can check it out and subscribe at the link below.