Excel Dashboard - Search Multiple Sheets & Calculate

I am creating an excel file for work where each deal we review will have an identical sheet that contains preset drop downs that are selected for specific questions. I want to have a dashboard sheet that provides the percentage that each drop down is selected.

For example each sheet will have a drop down that asks if the meeting started on time (B27 Yes/No). How do I have my dashboard search every B27 within each sheet and then spit out what percentage were answered no? The dashboard in this case would read "Percentage deals not started on time"

Please help!!!