If you're having trouble knowing exactly how much uplight the light fixtures on your site are emitting there is a simple free tool for converting an IES file into an output that will display uplight values in terms of Lumens, % of total fixture, and even the fixture's BUG classification.

Go to this page.
http://www.visual-3d.com/tools/photometricViewer/default.aspx
Click "Open". Then the brand names they have available files for will be listed. If you want the information for the IES file on your hard drive then click the "My Files" tab at the top.

The output will look like this.
http://www.visual-3d.com/tools/photometricViewer/default.aspx?id=13297

In the table called "Zonal Lumen Summary" in the 90-180 Zone, this is your uplight for that fixture.