Absolutely. The US also the home of what percentage of the IPv4 space? Must be a big part of that cake. With that very coarse view you'd expect them to be the last ones to need IPv6.
Comcast recently started rolling out IPv6 to standard residential accounts. I'm guessing a lot of people are now using IPv6 and didn't even notice.
Verizon Wireless is over 50% v6. My phone is v6. If I hadn't tried a "what's my IP" on my phone I wouldn't have noticed (which is how it should be).
And a staggeringly awful 0.24% in the UK.
Theres no real pressure here at the moment, so they won't do it in any hurry. Its not like theres a massive growth in houses being built.
But Germany and the US are both above 7%. I don't think the demographic pressures are greater in those countries; they just have more ISPs with competent network engineers.