In an interview Monday, Bill Samuels Jr. said he failed to foresee a worldwide surge in demand for premium bourbon when he was still in charge of the brand about six years ago. As a result, Maker's Mark is being diluted to 42 percent alcohol by volume, from 45 percent, so more of the whiskey can be bottled to meet demand. That's a cut from 90 proof to 84 proof.
http://www.usatoday.com/story/news/nation/2013/02/11/makers-mark-bourbon/1910773/