Those are some odd numbers they quote at the conclusion of the article...
By 2011, the Air Force improved to have its Ospreys ready 58 percent of the time and the Marine Corps 63 percent. Last year, those figures were up to 62 percent and 68 percent, respectively.
From
Seapower March 2011 - SPECIAL REPORT / MAINTENANCE, REPAIR & OVERHAUL:
While the availability rate of the Osprey in the field has remained
constant at just under 72 percent, the Marine Corps would like to
see 75 percent across the board