Betting on Keeneland racing through the first five days of the 17-day fall meeting is up 9.83 percent, track officials reported today.   Through Thursday’s racing, $37,054,751 had been bet on Keeneland’s fall meeting, an increase of $3,318,517 from a year ago when $33,736,234 was wagered on the comparable dates.   “The increases are a testimony to the outstanding quality of racing and large, competitive fields during opening weekend and during the first week of the meeting,” said Keeneland’s Director of Racing Rogers Beasley.  “The horsemen have been extremely supportive and the figures give us optimism for the remaining 12 days of the fall meeting.”   Keeneland’s FallStars weekend featured nine graded stakes races worth more than $3.25 million.