Base group stats on real CV (at least optionally)

Referring to pages like this: https://www.steamgifts.com/group/1TSzG/sgpillars/users

Using real CV is on average better to determine a user's contribution than the full price. So for groups it would be handy to have the stats available based on real CV.

Maybe it makes sense to keep the old way stats are calculated, and add an option to see it based on real CV.

Old discussion (closed): https://www.steamgifts.com/discussion/s2Wtv/group-statistics-question
Related comments: https://www.steamgifts.com/go/comment/TdndeMo