Those are world-wide numbers. Google reports 30% for the US: https://www.google.com/intl/en/ipv6/statistics.html#tab=per-....
My web server gets only 3,9% IPv6 traffic (based on counting unique IPs). Quite OK given that none of the major ISPs in my country offer IPv6 (neither on broadband or on mobile). Even for businesses it can be hard to get native IPv6 here.