Add an Average Value field in Collection

It would be nice to see/toggle a field in one's Collection which would show the current Average Value for each entry. For example, if you would have three copies of game X with a Total Value of $60, the Average Value would be $20. Needless to say one could use a calculator to perform such calculations each time but I feel it would be helpful to see such information automatically, especially with larger collections and for certain use cases.