Twitter Usage Stats: Where are the Bots?

SAI Business Insider's "Chart of the Day" shows a great series of graphics of Twitter usage

But where, or where are the Twitter Bots in this wonderful graph?

Those seemingly endlessly prolific Tweeters who have downloaded, purchased (yea, right), sorry meant pirated those 'Tweet Me Forever' bot programs.

Those "Hey Me! I can Tweet" Programs that bombard my Tweetdeck...