Extrapolating Missing Data

What specifically do you need help with?

If this is a "I have no idea where to begin" kind of thing, here's how I would analyze the data:
1) put the data in a spreadsheet -- level in one column and exp in a second column
2) Plot the data on a scatter plot with one column along the x axis and one column on the y axis.
3) Look at the chart and see if anything obvious becomes apparent.
3a) Switch X and or Y axes between linear an logarithmic to see if this causes the data to form a straight line
3b) compare the shape of the curve with the usual families of curves (quadratic, exponential, logarithmic, square root, etc.) that I recall from algebra/calculus. If you need a refresher on these: http://mathfortress.com/Precalculus/...0Functions.pdf
4) Hopefully at the end of step 3, I have some idea of what the regression equation should look like, so I set up the regression. Exactly how to set up this regression depends on my conclusions at the end of step 3.

With the problem broken down in steps, where do you get stuck?