First of all, you can't say "the U.S. total"; the proper phrase is "the entire U.S." The two numbered sentences should read:

1. The graphs above show the rates of electricity generation of Kansas and of the entire U.S. in 2010.
2. In 2010, the rate of electricity generation by nuclear power plants in Kansas was about the same as the rate for the entire U.S. [outside Kansas.]

In sentence 2, I've moved the date to the front of the sentence because otherwise it's too far from what it modifies.

That second sentence does not seem plausible, with or without the bracketed phrase. Do you mean "about the same as the rate for all other sources of energy in the entire U.S."?

In any case, I'm not tempted to use "that of" or "of that" in these sentences