Referring to Youtube Analytics API (Channel reports) Viewers demographic data
What is the base metric for calculated "viewersPercentage"?
Is it a sum of daily views on all channel videos or is it a sum of all-time views for this channel?
Thanks
You choose the base by specifying the report parameters startDate and endDate.
So if the startDate and endDate are the same, it will be the sum of daily views, otherwise it will be the sum of views of the date span.