This file contains only a few lines, and they are basically self-explanatory. All they do is alter the frequency of certain empires appearing when Spore generates a new spacefaring empire, be it uprisen with a monolith or generated with the galaxy as you explore.
For best results, it is recommended you erase your galaxy data when testing this type of mod -- otherwise results will not be noticeable enough.
The values contained in this file are weights, not probabilities. Thus, the values can be any size, and it will simply increase the chance. It is not recommended to raise the values too high, as Spore has memory limitations and may ignore the modification.