The current statistics for newsletter subscriptions in the moderator analytics tools show the number of users subscribing and unsubsribing every given day.
So I could easily see how many people subsribed and unsubscribed on a given day, but it is very hard to see e.g. the current number of subscribers. I'd argue that this is the value that would be most interesting, how many users are currently receiving the newsletter.
How many users subscribed or unsubscribed on a day would still be visible in the changes to the total number of subscriptions.
So, the graph in the analytics tools should show the total numbers of newsletter subscriptions, instead of the number of subscriptions and unsubscriptions on each day.