The Bitlocker Web Dashboard Trend shows Bitlocker complaince over a certain period of time depending on settings set. It scans to examine compliance for bitlocker in Active Directory, MBAM and ConfigMgr.
To setup Bitlocker Trend, navigate to Bitlocker dashboard.
In the upper right hand corner, click on the chart icon.
From the menu, you can select the date and time to schedule the snapshot.