To counter that a bit, the stock market has been on a tear lately with the S and P up over 30% in 2013. I know quote a few gummers who were over weighted in stocks and after the last couple of years of out sized returns are now much closer to pulling the trigger on retirement.I would add that you can't use the old statistics for guys going early for medical issues.
While you would think that going early for medical reasons would be fairly cut and dried, the reality is that it isn't.
Back in the day, say 1999, lets use the example of a 57 YO dude (or dudette). They had a medical issue that grounds them. They have 1800 hours of sick time saved up, plus LTD. They could easily coast to age 60 with practically no loss in pay, and still receive their full DB.
Even if they were younger, say 55, sick leave and LTD would probably take them to 58, then go to a medical retirement, with little or no penalty.
With those sets of financial circumstances, my guess is unless they had some kind of overriding personal desire to go back to work, they could just retire and be done with it. Depending on when they got hired and the nature of the DB plan, working extra may not even add to their accrued benefit.
Sure, they could try to get their medical back, but it was hardly the end of the world if they didn't, and so the effort expended was probably fairly modest. My guess is that's what accounted for rather large percentage of folks that didn't make it to 60.
These days, there is no DB plan to coast into, and as a result, people are far, far more aggressive in regaining their medicals. As a result, not only are the pilots who are working staying until 65, but a far larger percentage of those who would nominally have coasted off into the sunset, are coming back to work.