Y deme's population was steady at 9416 before it decreased to 5937 4348.107 generations ago, maintaining that number to the present.
time_units: generations
demes:
  - name: Y
    start_time: .inf
    epochs:
      - start_size: 9416
        end_time: 4348.107
      - start_size: 5937
        end_time: 0