How to calculate the very basics incredible basics

[#1]

I have a data set and use tabulate to summarize the data and publish in the exportable interactive HTML form (implementing in a website where exporting to excel does not help).

However I am unable to do it. The bottom tabulate takes the mean of several rows and I need as an aggregate the sum of those means which should be 827102,270 or vica versa

I could add the sum of rows and I would need the mean of those sums but it also seems to be impossible. Does anyone have any idea rather than making a summary table creating a new column adding formula recalculating and still not being able to export as Ineractive HTML of the tabulate?