D deme's population was steady at 6117 before it changed to 6900 7262.4 generations ago, maintaining that number to the present.
time_units: generations
demes:
  - name: D
    start_time: .inf
    epochs:
      - start_size: 6117
        end_time: 7262.4
      - start_size: 6900
        end_time: 0