You probably need to apply a seasonal factor as well. If you ask the boys for the period of say mid-December to mid-January (the true "high season") you'll likely find a higher percentage with an "off" most days. That is because the annual visitor tends to arrive, pick a boy and keep him for the duration of his holiday, and then fly home. That's probably about 18 - 20 "offs" in a 4-week period, since the punter usually pays the bar by the day