There are a few Content Blocks that I am re-using in many different emails and I would like to know the overall performance in terms of clicks activity.
For example, if we have a block (an Image with a URL) that was sent in the past 10 emails, to see what is the overall CTR rate.
I think what you are looking for is Impression Regions/Tracking. You would grab your block and add the AMPscript into it to set the region for each email it is used in.
Once you add this in to each of your blocks, you should be able to aggregate data from the OOTB reports (e.g. this one) in SFMC related to Impression regions to give you overall numbers for that region.
This answer and this answer have some relevant more detailed info that may assist you.
Outside that, you could just look for the link alias/url (if it is unique) in the _Click data view and count the totals there versus the total sent across each of the email jobs including that content block. But keep in mind this will only give a 6 month lookback.
