You could do this by doing a query based on the date field, there are examples of this available. Then if you have a repeater somewhere, like on an options page, you can add rows to that repeater.
But this sounds a little complicated to me to track how many posts there are per year. I would more than likely create a WP options value that contains an array and track how many posts are created for each year as they are created or updated. If I need to do this retroactively then I’d find a way to get and populate this list and then start adding to it.
