By default, Microsoft Project does not have a baseline percent (%) complete field or column like you would find in other scheduling software like Primavera P6.

This video outlines steps to follow if you want to display a baseline percent (%) complete column in a Microsoft Project schedule. It also shows how to roll-up percent (%) complete to summary tasks based on weighted percent (%) complete of the subtasks and this method in my opinion is better than summary task percent (%) complete using average of subtasks percent (%) complete or summary tasks baseline start and baseline finish dates.