The UI for vital signs will no longer display legacy pageview data (pageviews calculations that used the old definition). We are working towards having one consistent pageview definition [1] in every tool that surfaces pageview data.
Please have in mind that the new definition only exists since May 2015 any data from before the switch was made was calculated using the old (undocumented as far as we know) definition.
You can access vital signs UI in the following url: