I have the following chart

<http://jsfiddle.net/hcJjX/2/>

If you notice the y-axis values are always '0' here. But the line is drawn in the middle of the chart. However, I want the line to be drawn on top of the 'x-axis' as follows (as it would be if there were atleast one non-zero value):

<http://jsfiddle.net/hcJjX/2/>

Is there something I am missing here?