Duration Curve

[hip2b2]

I am trying to create a Duration Curve, ie, a Scatter Graph consisting of hundreds if not thousands of data points plotted against sequential days (operating time).

I need to be able to determine the value at 10% of the operating time (which may not be an integer) and draw a horizontal line across the chart where that value intersects the data line.

I can send an example of what the chart needs to look like (I can't seem to attach a jpg) if anyone asks.


Thanks in advance.