This is a great idea, and I have been thinking about it for a long time! RTM has some very rudimentary instruments for that (i.e. viewing completed tasks and also at the end of the year prompting to post how much has been completed over the year. But this is very basic, and so much more can be done.

For example, same should be viable per individual tab/hashtags. Then I would also include stats on how many and which types of tasks are postponed or deleted. Or for how long they are delayed.

Frankly, I am a bit disappointed that the app has been hardly developing in the past couple of years. It offers a solid toolkit for productivity management, but that does not mean that things should stop there and there is no room for development...