This is the example where you're taxing 10%, my scenario is much more friendly, but as you can see the curve is pretty identical, only less accentuated. There's obvious no purpose in showing you a 0% graph, but you might want to contrast this one with the 100% one.
IRS 2012 in Portugal: how many € people earn monthly vs. how much they get (after taxes collection)
Grab the code here. The presentation was inspired by one of Raphaël's demos...