Flew FRA-BUD last autumn, on A.321, only myself in C for the late evening flight out of FRA. Whole front section all empty. Another story in the Y part...but I think at least the first 12 rows or so was only me!, but looked quite full in behind.
Also made BRU-FRA on the 28th Dec last year. Think we were 6 or seven on a 737-500 leaving BRU early in the morning.....very goods service on that short flight.