This report drills into Skype for Business usage in more detail than the data expressed in the Office 365 activity report. The Activity panel shows the number of sessions by type, and the Users panel shows unique users by activity type. Types include Peer-to-peer (for example, IM/chat) session, Organized (meeting host), and Participant (meeting attendee):
A normal pattern of adoption will show more peer-to-peer activity than meetings and (somewhat obviously) ...