A couple of articles are showing up in the current news cycle, though these are not really "new" in the content within:
{Washington} Examiner Editorial: If top 5% paid 40% of taxes, what is their 'fair' share?
The Millionaires Who Pay the Highest Tax Rate
In answer to the first question (headline), the answer is not "more", though that is certainly what the occupant of the Whitehouse, and many of his Democrat brothers and sisters want us all to believe and act upon.
The second article that I've linked is interesting in discussing the point at which the tax collection from "high earners" starts dropping -- when they make more on investments and less on traditional income. That might be an area that some would say needs to be fixed, but I'm not so quick to want to join them. At least not in the way that the progressive side would want, and honestly, not necessarily in a way that the conservative side would like.
Personally, I'd love to see short-term speculation addressed with taxes that hit short-term investors hard. Short-term capital gains seems to me to mostly be legal loan sharking. I'd be happy if investments that were flipped in under 30 days were taxed at what others would call outrageously high rates. From there, use a sliding scale that reduces taxes on investments as the investments sit. Basically reward long-term investment at the expense of those that profiteer in the short-term investment world. I'd like a realistic number for the longer term investments, and maybe, just maybe, use a sliding scale on the longer end so that money does move around within the market and not just sit permanently (maybe hit investments that are longer than say 5 years at rates that start to rise depending upon how long the money sits).
In anycase, the answer -- for the most part -- on taxes continues to be one that Democrats don't want to hear -- you can't tax the rich to keep paying for all of your spending. You already have been doing it, despite the continued psychological and class warfare that the Democrats continue to rely upon inciting their followers with: TAX THE RICH. Yeah, just say it loud and they circle around and start sniffing for the blood like a pool of sharks. Yeah, yeah, we need to get that rich man to pay their fair share. They aren't doing enough to make life easier on, well, everyone at the low end of the scale. Except, well, they are all already taking on the tax burden of several individuals all by their lonesome.
What is the right number? Should a typical "rich" person be left carrying the burden of 3 other individuals? Is that OK? If so, then Mr. Buffet and his friend in the White House aren't going to be happy because they'll wind up losing how much revenue from that same Mr. Buffet or from Mitt Romney, Bill Gates, etc. Is 5 other individuals enough? How about 10? 100? What is the right number here, come on Democrats, tell us what that number is.
Oh, wait. I forgot, in Democrat-world, that number is *all*. It's 99.9999 percent. Really, we just need one individual to do all of the work, make all of the money, and take care of the rest of the world. Isn't that right?
Bleh.