When is a Keyword a Popular Keyword?

I have been patiently waiting for stats to churn out of my Google Coop Custom Search for the other site I manage. But same as what I was receiving in the past few months, the message says “No queries were sufficiently popular to be listed.”

Maybe the number of queries were not enough to properly distinguish which phrases (or keywords used within these phrases) are more popular than the others. But the question is what’s the numerical qualifier that triggers a phrase to be popular in Google Custom Search?

I end up using the data extracted from Google Webmaster tools.

I am positive though that the enhance custom search will make a difference.