If you haven't gotten the idea so far, it's time we just said it: Grammar changes. Words are fluid and don't mean the same thing forever, nor are they used the same way throughout eternity. Fittingly, we come to "hopefully," which became a flash point for some grammar wars a few years ago.
"Hopefully" literally means "in a hopeful manner." That means that using it in the sense of "it is hoped" is incorrect, as in "Hopefully it will rain soon." In that instance, you're really saying, "In a hopeful manner, it will rain." However, the sentence "We watched the clouds hopefully for rain" is correct.
Or something like that. The point is, there's a very commonly accepted usage where we mean "it is hoped" when we say "hopefully." So when the Associated Press decided in 2012 that it would begin accepting "hopefully" in such a manner, anarchy reigned. Or at least some people wrote some angry editorials that are totally worth reading.