Avg. training time to certify per national training data base for years 2009- through 2012 (averaged by like facilities for Terminal, individual numbers for EnRoute)
It's what they call the "training cycle". It's an input for projecting staffing, not an number that accurately reflects actual time-to-certify. Centers are 3 yrs, (most) up/downs and tracons are 2, (most) towers are 1.