cannot find return visits and new visits in "Add metrics" in SC 15

I would like to build a report in SC 15 to show new visits and return visits of pages. In other words, I would like the report to show 2 metrics: new visits and return visits. If % can show up, that will be better. 

However, when I go to Site Content >Pages, and click "Add Metrics", I could not find new visits or return visits in the "Available metrics" drop down menu.

What should I do in order to add return visits and new visits into my report?

Thanks a lot!