Count PHP Subarray

I have an array in PHP in the format


Array (     
[0] => Array ( [class] => 14  [Owner] => 89)
[1] => Array ( [class] => 15  [Owner] => 6634)    
[2] => Array ( [class] => 15  [Owner] => 6837)
...
)

I would like to get a count of how many elements are in each class; e.g.how many class 15 elements are in the array.

TIA,
Doug