[Users] How Effective is STUN?

[Tavis P]

I'm trying to find some statistics as to what the ratio of Cone vs
Symmetric NAT solutions deployed in the world are, has anyone done some
research into this?

I'm curious what percentage of users in certain demographics (broadband
clients, for example) i can expect to be serviced using STUN alone, so i
can come up with some figure to help me build out my network

Even just some anecdotal information of peoples experiences would be
very useful

Tavis