Of 16 colonies here in central Maine:

 11 are beautiful
  1 got weakened by a mice but will be OK with excess brood from strong neighbor
  1 an apparent recent queen failure with at least 5# of bees, getting new queen
  1 late September 1999 split is weak due to a queen with spotty pattern
  1 weak, queen with spotty pattern, will be combined with the one above and
given
    excess neighbor brood plus new queen
  1 effectively dead, handful of bees and queen, was same last year, very
disease
    prone, suspect trachael mites.

So in summary, with care, losses of 2 in 16, or 12%.