Cyptolocker - U.S. specifically targeted

[Poseidon]

Looks like United States was specifically targeted by Cryptolocker. From an older technet blog:

. . .Crilock has predominantly affected English-speaking countries, although it does have a comparatively small presence in non-English speaking locations as well. Every Crilock variant we’ve seen so far has a ransom message written only in English.

[Ferrit]

Possibly the US is seen as being more likely to pay??