Has anyone got details on how to use the rank value as more than a means for ordering. I am currently trying to use the value to create a relevance bar.

At present a relevant rank value can change (normaly from around 30 to 200). As a result at the moment I am assuming that the top value is a relevant match and effectivly dividing all ranks this value and multiplying by 100 to get a percentage. This of course only works if the top record returned is actually relevant.

I'm sure there must be better ways of doing this, any ideas?