Not sure we understood each other well here. My intention is to display the number of domains on the blocklist for which queries have actually been blocked. Or in other words, what domains on the blocklist have been requested by your network's clients.
Example: You have a gigantic blocklist of 5 million domains. However, in reality you need far less to effectively block ads and other unwanted stuff. Such tool you help to identify the domains need to be blocked (by identifying which ones have been requested by your client).
I think this is interesting, quantify the numbers and identify the relevant domains blocked.
As far as I understood, the feature request is about the number of unique blocked domains. Let's say gravity contains 5 Million domains, 1 Million queries have been blocked, but only 1000 different (unique) domains (each 1000 times).
In the end one could say there is no need to have 5 Million domains in gravity, for this network 1000 domains would have been sufficient.