title: What is a good way to get historical Twitter follower numbers?
body: <p>I need the historical numbers of followers for a set of 60 Twitter users. Unfortunately the official Twitter API only returns the most current follower count. I know that there is probably no one-size-fit all and fool-proof way to get an accurate follower growth graph for all users in my list. However, would there be a good and logical way to estimate or deduce this based on other information available through Twitter API (e.g. number of retweets, likes)?  I read somewhere that retweet rate grows proportionally with number of followers. </p>
  
  <p>Any help or advice would be much appreciated. Thanks! </p>