Up until 6075.505 generations ago, the count of X deme was 1528. Following that period, it grew to 6656, where it has persisted until now.
time_units: generations
demes:
  - name: X
    start_time: .inf
    epochs:
      - start_size: 1528
        end_time: 6075.505
      - start_size: 6656
        end_time: 0