The increases in the U.S. are not surprising. As someone else (I think it was OTWO) pointed out, the increase in bible studies can likely be attributed to the new policy of allowing both parents to count the family study. Previously only the "family head" could count it. [edit: as sir82 pointed out, this isn't correct--the new policy is that the other parent can count the time, not the study]
Also, the increase in publishers and memorial attenders is not surprising and may continue for a few more years. As long as there is significant immigration to the U.S. from Latin American countries, I expect to see an increase in U.S. publishers. For whatever reason, Latinos seem to be unusually receptive to the WTS message. It's probably a combination of (1) coming from a religious background, (2) seeing the hypocrisy in that religion (usually Roman Catholicism), and (3) being an immigrant in a new country desiring to find a social network--a place to fit in.