For deme Y, the population count was 2919 until a change 6644.6579 generations ago, where it decreased to 1238, remaining steady thereafter.
time_units: generations
demes:
  - name: Y
    start_time: .inf
    epochs:
      - start_size: 2919
        end_time: 6644.6579
      - start_size: 1238
        end_time: 0