I don't know about the other carriers, but at NWA, it is like this:
As of 1 Jan 06:

Retirements in the next 6 Months = 56
12 Months = 146
18 Months = 225
24 Months = 344
36 Months = 524

It assumes all pilots retire in the month they turn 60. Also we currently have 700 pilots on furlough and 92 who are Ropes. So, "your mileage may vary."