Google quietly announced on Google+ yesterday that the Keyword Planner tool within Google AdWords is being upgraded to add benchmark data so you can compare your performance to your competitors.

Google said it is rolling out over the next few weeks. The feature is “enhancing the Keyword Planner to help you compare your search term coverage to other advertisers,” said Google.

(1) You can now review your relative ad impression share compared to the top five market leaders across all your generated keyword ideas:

(2) You can now review your relative ad impression share compared to similar advertisers in various keyword categories:

Google explains in more detail:

Forum discussion at Google+.