Passenger numbers were flat at budget airline Easyjet in January, while planes were not as full as they were a year earlier.The carrier flew just over 4.02m customers last month, representing no change from January 2014.Because Easyjet is a no-refund airline, it measures passengers as the number of earned seats flown, regardless of whether or not the customer is a no-show.Meanwhile, the load factor, which represents the number of passengers as a proportion of number of seats available, was 85.1% in January, down 30 basis points on the year before.Easy jet's shares were down 1% at 1,760p by 08:40 on Thursday.