Conditional Area Series Background in Asp.Net Charts

I am displaying account balances by month by using a asp.net chart with a SplineArea series. If the balance is positive I want the SplineArea to have a green backg开发者_如何学编程round but if the balance is negative I want the background to be red. (i.e. positive y value is green, negative y value is red)

How can this be done?

use a binding directly or with a converter that gives a color depending on the value being positive or negative