Completion rate Scorecard in Looker Studio ?

[mulleo]

I have a data source that has entries as follows: 

Task name            Status
Task1                        Not started
Task2                       Ongoing
Task3                       Done
Task4                       Done
Task5                       Not started

I would like to create a Scorecard, that states "Completion rate: 40%", based on how many tasks are in status done. How do I create this? I have tried to search the help page, but seem to find only instructions for numeric fields..  😕

[sam8]

Maybe create a calculated field that counts the number of DONE records and divides by the total number of records?

SUM(IF(status=done, 1, 0))/COUNT(task name)