Jim Dandy: I believe the actual stats are about 2 per day here in the U.S.  I'm not trying to be reactionary or alarmist--just presenting the numbers.

As far as the sources of the numbers, I think that here in the U.S. we've only got really solid stats from the following tracks (participants in the on-track injury reporting system):
Albuquerque
Aqueduct
Arlington Park
Bay Meadows
Belmont Park
Calder Race Course
Canterbury Park
Churchill Downs
Colonial Downs
Del Mar
Delaware Park
Delta Downs
Ellis Park
Emerald Downs
Evangeline Downs
Fair Grounds
Fonner Park
Golden Gate
Gulfstream Park
Hawthorne Race Course
Hollywood Park
Hoosier Park
Indiana Downs
Keeneland Racing Association
Kentucky Downs
Laurel Park
Lone Star Park
Louisiana Downs
Meadowlands
Monmouth Park
Oak Tree Racing Association
Penn National
Pimlico Race Course
Philadelphia Park
Portland Meadows
Prairie Meadows
Presque Isle Downs
Remington Park
Retama Park
Sam Houston Race Park
Santa Anita Park
Saratoga
Suffolk Downs
Thistledown
Timonium
Turfway Park
Woodbine
Woodlands
Yavapai Downs

I think I may have made a mistake in understanding what constitutes a "start".  I took that to mean each individual horse in a race, whereas the stats might apply to each individual race (no matter how many horses are in it).  The best current numbers for dirt tracks are almost exactly 2 deaths per 1,000 "starts".

Others can argue about what is rare or excessive.  I'm taking an agnostic stance for the moment, until I've got more solid information.