According to the International Civil Aviation Organization, from 2010 to 2013 there were 20,000 unruly passenger reports with 2013 accounting for about 8,000 of them. These reports consist of "physical assault, failing to follow direction, consumption of illegal narcotics, sexual harassment and physical or verbal confrontation." Now, not all of them resulted in a flight diversion, but there's little doubt that air rage mixed with copious amounts of alcohol were involved in a majority of them.
The ICAO sites a specific trans-Pacific flight in 2011 carrying two excessively drunk business execs who were so severely physically and verbally abusive to the crew and passengers that the plane had to be diverted. This ultimately cost the airline around $200,000; that's a hefty price to pay when profit margins are barely running on fumes.
From this discussion the Montréal Protocol 2014 was introduced; this is an amendment to the 1963 protocol for the same situations, now giving airport staff more control to deny boarding (and further drinks) to any passengers that might have drank a bit too much. The 78-page document (available in 6 different languages) also proposes to extend the right to prosecute offenses to the flight’s destination country instead of the airplane's country of registration, and gives the captain of the plane a lot more power when serious offenses are committed.
Right now, the Protocol needs to be agreed upon and signed off by the 240 airline members, government representatives and airports until it's fully enacted, so nothing much will change in the near future. In the meantime, if you still need a little help on being a pleasant passenger, re-read these eight tips to happy flying.