Neteller reported they processed $7.3 billion in 2005. If the market was around 12 billion that year you can guestimate what their actual percentage was.
Heres a quote from a news report posted at Gambling911
Quote:
Full Tilt Poker depended on NETeller for 75 percent of transactions, and the world’s biggest site, Pokerstars, used NETeller for around 60 percent of wagers.
Those are much closer to the actual numbers one would expect then 10%