Some stats I collated for JP:
'09 500: 44 qualifying entries, 37.00 cut off (with Spazz last)
'10 500: 34 qualifying entries, 37.02 cut off (SC Steve last)
'11 500: 37 qualifying entries (inc. DQ), 37.025 cut off (37.02 without DQ)
Currently as of 1911 BST
'12 500: 39 qualifying entries, 37.0050 cut off.
'09 500: 44 qualifying entries, 37.00 cut off (with Spazz last)
'10 500: 34 qualifying entries, 37.02 cut off (SC Steve last)
'11 500: 37 qualifying entries (inc. DQ), 37.025 cut off (37.02 without DQ)
Currently as of 1911 BST
'12 500: 39 qualifying entries, 37.0050 cut off.