[tor-relays] How to determine demand/need for bridges/PT?

Looking at the Tor Metrics page, I can see the number of bridges and the number of users connecting via bridges, but that's not enough information to determine satisfaction of demand.

Are there now enough bridges to comfortably satisfy demand? Enough bridges with a particular PT type? If not, what kind of resources are lacking?

How does one determine where the need for more bridges, or PT type, is greatest? (Assuming that there is any unmet need at all.)