wealthy households are indeed paying a significantly higher share of federal income taxes than they used to...."Used to" as in, before a Republican Congress?
I'm not following your point. Are you saying that the Republicans made a point of increasing taxes on the wealthy?
We only had a Republican Congress from 1995 to 2001, anyway, and that only narrowly so. Whereas, we're talking about tax and income changes that have taken place over the last quarter century.