Creating a Measure to Divide 2 Columns in a Pivot Table

[ziggle]

Hi folks,

I am looking at some oat production data from the USDA. I have been able to compute yield (=Production/Harvest acres) using calculated fields and in PQ. It seems like I should be able to compute the yield using a measure, but I have been stumped. When I am in the measures dialog, I see the type as a column option, but not harvested or production. How do I get access to these items so I can perform the division.

Here is an excerpt from the table. As I said, I can compute the yield a couple of ways, but I am wondering how to use a measure to compute it.
<table>
<tr>
<td>Sum of Value</td><td colspan="4">Type</td>
</tr>
<tr>
<td>State</td><td>Harvested</td><td>Planted</td><td>Production<td>Yield</td>
</tr>
<tr>
<td>North Dakota</td><td>105</td><td>300</td><td>8610<td>82</td>
</tr>
<tr>
<td>South Dakota</td><td>95</td><td>290</td><td>7790<td>82</td>
</tr>
<td>Minnesota</td><td>105</td><td>180</td><td>6195<td>59</td>
</tr>
</table>