AUBURN, Wash. – Business is booming at Emerald Downs. The midpoint of the 70-day meeting came and went Friday, and both average field size – spurred by a 20 percent increase in overnight purses – and betting handle have jumped dramatically from the corresponding date in 2014. Ron Crockett, the former president of Emerald Downs who now serves as a consultant to the track’s owner, the Muckleshoot Tribe, said betting on Emerald’s races from all sources was up 18.5 percent through last Sunday to an average of $854,924 per day. That towers over the average of $721,373 at the same point a year ago and would seem to bode well for the Muckleshoots, who assumed ownership of Emerald Downs this year.“They invested in various incentives that have worked,” Crockett said of the new ownership group and its management team, led by track president Phil Ziegler. “That’s basically it. The horse population has been running over 1,000, compared to maybe 820 in previous years at this time. There are new faces here who I would expect to stay the meet and return the following year. I have no reason to believe differently.”Emerald’s races attracted 6.27 starters per race in 2014. The average has swelled 8 percent to 6.82 at the current meeting. After a predictably slow first few weeks, things picked up when a handful of trainers arrived from Turf Paradise in May. Since June 1, Emerald’s average field size has been 7.12 runners per race.