Hey @Mihow,
I did some digging and you actually need to have Asana support manually add this integration to your domain (you must also be premium). You can have support add it by filling out this form. (cc: @keeeith, @James_Carl)
Another option is to see if any of the reporting apps will solve your use case.
You could also have a developer write a script to create your custom report via the Asana API. All of the data you need for your report is accessible through the API. (It’s also accessible via a saved advanced search in the product, though getting a count isn’t always perfectly seamless re: Simple task total report)
Cheers!
Jeff