Query: How much was casino revenue in 2013?
Context: In the wake of the closures and declining revenue from casinos, Governor Christie said in September 2014 that the state would consider a 2015 referendum to end the 40-year-old monopoly that Atlantic City holds on casino gambling and allowing gambling in other municipalities. With casino revenue declining from $5.2 billion in 2006 to $2.9 billion in 2013, the state saw a drop in money from its 8% tax on those earnings, which is used to fund programs for senior citizens and the disabled.