Forum for users that want to write their own custom queries against the PT database either via the Structured Query Language (SQL) or using the PT3 custom stats/reports interface.
That stat isn't built in by default but you can download it and import it into PT3 from this link. To import click Configure --> Configure Statisitcs, go to the Statistics tab and click Import. Choose the downloaded file and click OK, then Apply after it's done. Once you've updated your cache, you'll be all set to use this new stat.