The FIT Rate for the CY2309 is 16 FITs as per the Qualification Report number 98204 that applies. Accordingly, mean time between failure can be calculated as follows:
MTBF = 1 / [(FIT X 10^-9) hours x 24 (hours/day) x 365 (days/year)].
This roughly amounts to 7,135 years or 6,25,00,000 hours for the CY2305SXC-1. Attached are the qualification reports that provide the FIT Rates.