Multiline charts with interpolation

Hi, I’m trying to find a plugin that create a multiline chart like the image I’m showing:

But, I’m not being able to find one that can interpolate values. The problem is that I have three lines to compare on the same chart, but most of the time the points won’t be registered in the same date.

I can’t set “0” values because it will change dramatically the chart and empty values normally break the lines. I need a plugin that accept empty values and continue with the line in the same slop.

I’ll really appreciate your help.