Up until 5507.031 generations ago, the count of Z deme was 9968. Following that period, it decreased to 7705, where it has persisted until now.
time_units: generations
demes:
  - name: Z
    start_time: .inf
    epochs:
      - start_size: 9968
        end_time: 5507.031
      - start_size: 7705
        end_time: 0