Averaging SUM Fields

[Niet32]

I have 5 markets that are summed.

4 of the 5 markets have data, one doesn't because of the store being closed for renovations.

I want to get an average sale per market but not include markets that have 0 sales.

The problem is when I use the average function it includes the market that has no sales.

How do you get it to average a SUM field with greater than 0 sales?

Thanks

[sbg2]

Example of the formula you are using?