Twitter activity is highly concentrated among a small subset of heavy users, according to an analysis from researchers at the University of Illinois, published in First Monday. The study used Twitter Decahose as the basis of its analysis, with the data set examined over a period of 39 days constituting about 0.9% of Tweets ever sent and 35.6% of all active users as of December 2012. Among the highlights of the study was the revelation that the top 1% of Twitter users accounted for 20% of all tweets. Expanding that out a little, the top 5% accounted for 48% of all tweets and the top 15% accounted for 85%.