Ryanair passenger numbers increased 2% to 81.4 million in 2013.
This compares with a 4% rise in 2012.
The Irish budget carrier's load factor kinked up from 82% to 83% last year. In December, passengers numbers rose 4% from the same month of 2012, to 4.8 million.
Ryanair has lately embarked on a customer-service drive, introducing a host of new policies. It has granted passengers permission to bring a second small carry-on bag on board, cut the boarding-card reissue fee, introduced a 24h grace period to correct minor booking errors, and rolled out allocated seating.
The carrier is also shifting its focus away from out-of-town airports by adding services to Brussels Zaventem and Rome Fiumicino in a bid to attract higher-yielding traffic.
Average fares were 2% down in the half-year ending 30 September, though "revenue per customer" was up 2%.