Different colours of a line depending on its value

[#1]

Hi, I don`y konw if this can be done in QV so i ask you everybody:

I have a Graphic lines with shows the Incomes Amount as a line graph. The months are on the X-axis, the Amount Value in the Y-axis, and the Field Year is the series

What I'm trying to do is that the line of the 2011 year has a green colour when Its above the 2010. (In general the current year regarding the last year) and a red colour when It's belove. I mean, a line with two colours depending on its value.

Thanks a lot for your replys.