Right. But I assumed that the ranking was supposed to be an indication or some sort of SEO value.
Let's assume that lower rank is "better."
You could average the parameters (ranks) replacing dashes with large penalizing ordinal numbers (11's say). Average the 5 ranks and sort from lowest to highest to narrow down a vary large list to the "better" keyphrase.
Meg, are you implying that this isn't worth doing because those ranks don't mean much? I wouldn't know, you tell me.