As miniDBA samples server performance it saves results to a log which can be read by the history viewer and the contents displayed for later analysis.
First click the history button at the bottom left of miniDBA:
Then select the instance and dates(s) to view. These lists will be comprised of every instance and date miniDBA has ever logged on:
The screenshot belows shows an opened server history , displaying the main dashboard view on the right.
There are 4 other tabs in the history viewer that have individual displays of other historic data: