From October 1, 2013 to September 30, 2014:
slot machines: $6.71b
baccarat: $1.65b
blackjack: $1.08b
craps: $0.37b
roulette: $0.33b
I always knew slots were legit but seeing the numbers side-by-side never ceases to amaze me.
source: http://gaming.nv.gov/index.aspx?page=149