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      "switch_utc": "2022-02-20T23:00:00+00:00",
      "difference": -0.015000000000000568
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    {
      "from_contract": "ZCK22-CBOT",
      "to_contract": "ZCN22-CBOT",
      "decision_session": "2022-04-13",
      "old_volume": 46066,
      "new_volume": 48100,
      "switch_utc": "2022-04-13T22:00:00+00:00",
      "difference": -0.0600000000000005
    },
    {
      "from_contract": "ZCN22-CBOT",
      "to_contract": "ZCU22-CBOT",
      "decision_session": "2022-06-27",
      "old_volume": 43765,
      "new_volume": 59200,
      "switch_utc": "2022-06-27T22:00:00+00:00",
      "difference": -0.8224999999999998
    },
    {
      "from_contract": "ZCU22-CBOT",
      "to_contract": "ZCZ22-CBOT",
      "decision_session": "2022-08-15",
      "old_volume": 30055,
      "new_volume": 93943,
      "switch_utc": "2022-08-15T22:00:00+00:00",
      "difference": 0.012500000000000178
    },
    {
      "from_contract": "ZCZ22-CBOT",
      "to_contract": "ZCH23-CBOT",
      "decision_session": "2022-11-22",
      "old_volume": 37367,
      "new_volume": 56802,
      "switch_utc": "2022-11-22T23:00:00+00:00",
      "difference": 0.022499999999999964
    },
    {
      "from_contract": "ZCH23-CBOT",
      "to_contract": "ZCK23-CBOT",
      "decision_session": "2023-02-21",
      "old_volume": 46297,
      "new_volume": 67242,
      "switch_utc": "2023-02-21T23:00:00+00:00",
      "difference": -0.004999999999999893
    },
    {
      "from_contract": "ZCK23-CBOT",
      "to_contract": "ZCN23-CBOT",
      "decision_session": "2023-04-18",
      "old_volume": 65120,
      "new_volume": 82986,
      "switch_utc": "2023-04-18T22:00:00+00:00",
      "difference": -0.3324999999999996
    },
    {
      "from_contract": "ZCN23-CBOT",
      "to_contract": "ZCU23-CBOT",
      "decision_session": "2023-06-21",
      "old_volume": 82971,
      "new_volume": 85433,
      "switch_utc": "2023-06-21T22:00:00+00:00",
      "difference": -0.46500000000000075
    },
    {
      "from_contract": "ZCU23-CBOT",
      "to_contract": "ZCZ23-CBOT",
      "decision_session": "2023-08-15",
      "old_volume": 35104,
      "new_volume": 93015,
      "switch_utc": "2023-08-15T22:00:00+00:00",
      "difference": 0.1175000000000006
    },
    {
      "from_contract": "ZCZ23-CBOT",
      "to_contract": "ZCH24-CBOT",
      "decision_session": "2023-11-22",
      "old_volume": 53449,
      "new_volume": 70938,
      "switch_utc": "2023-11-22T23:00:00+00:00",
      "difference": 0.1900000000000004
    },
    {
      "from_contract": "ZCH24-CBOT",
      "to_contract": "ZCK24-CBOT",
      "decision_session": "2024-02-22",
      "old_volume": 85254,
      "new_volume": 111302,
      "switch_utc": "2024-02-22T23:00:00+00:00",
      "difference": 0.125
    },
    {
      "from_contract": "ZCK24-CBOT",
      "to_contract": "ZCN24-CBOT",
      "decision_session": "2024-04-22",
      "old_volume": 89214,
      "new_volume": 113324,
      "switch_utc": "2024-04-22T22:00:00+00:00",
      "difference": 0.09999999999999964
    },
    {
      "from_contract": "ZCN24-CBOT",
      "to_contract": "ZCU24-CBOT",
      "decision_session": "2024-06-25",
      "old_volume": 51683,
      "new_volume": 83942,
      "switch_utc": "2024-06-25T22:00:00+00:00",
      "difference": 0.0625
    },
    {
      "from_contract": "ZCU24-CBOT",
      "to_contract": "ZCZ24-CBOT",
      "decision_session": "2024-08-14",
      "old_volume": 51258,
      "new_volume": 97531,
      "switch_utc": "2024-08-14T22:00:00+00:00",
      "difference": 0.20250000000000012
    },
    {
      "from_contract": "ZCZ24-CBOT",
      "to_contract": "ZCH25-CBOT",
      "decision_session": "2024-11-21",
      "old_volume": 66470,
      "new_volume": 86171,
      "switch_utc": "2024-11-21T23:00:00+00:00",
      "difference": 0.09500000000000064
    },
    {
      "from_contract": "ZCH25-CBOT",
      "to_contract": "ZCK25-CBOT",
      "decision_session": "2025-02-20",
      "old_volume": 62320,
      "new_volume": 73448,
      "switch_utc": "2025-02-20T23:00:00+00:00",
      "difference": 0.14250000000000007
    },
    {
      "from_contract": "ZCK25-CBOT",
      "to_contract": "ZCN25-CBOT",
      "decision_session": "2025-04-16",
      "old_volume": 71432,
      "new_volume": 73036,
      "switch_utc": "2025-04-16T22:00:00+00:00",
      "difference": 0.07249999999999979
    },
    {
      "from_contract": "ZCN25-CBOT",
      "to_contract": "ZCU25-CBOT",
      "decision_session": "2025-06-24",
      "old_volume": 39095,
      "new_volume": 61524,
      "switch_utc": "2025-06-24T22:00:00+00:00",
      "difference": -0.03250000000000064
    },
    {
      "from_contract": "ZCU25-CBOT",
      "to_contract": "ZCZ25-CBOT",
      "decision_session": "2025-08-13",
      "old_volume": 43421,
      "new_volume": 109235,
      "switch_utc": "2025-08-13T22:00:00+00:00",
      "difference": 0.23999999999999977
    },
    {
      "from_contract": "ZCZ25-CBOT",
      "to_contract": "ZCH26-CBOT",
      "decision_session": "2025-11-20",
      "old_volume": 72080,
      "new_volume": 116479,
      "switch_utc": "2025-11-20T23:00:00+00:00",
      "difference": 0.11250000000000071
    },
    {
      "from_contract": "ZCH26-CBOT",
      "to_contract": "ZCK26-CBOT",
      "decision_session": "2026-02-20",
      "old_volume": 93795,
      "new_volume": 115702,
      "switch_utc": "2026-02-22T23:00:00+00:00",
      "difference": 0.1200000000000001
    },
    {
      "from_contract": "ZCK26-CBOT",
      "to_contract": "ZCN26-CBOT",
      "decision_session": "2026-04-21",
      "old_volume": 57264,
      "new_volume": 73282,
      "switch_utc": "2026-04-21T22:00:00+00:00",
      "difference": 0.08000000000000007
    },
    {
      "from_contract": "ZCN26-CBOT",
      "to_contract": "ZCU26-CBOT",
      "decision_session": "2026-06-24",
      "old_volume": 41521,
      "new_volume": 48992,
      "switch_utc": "2026-06-24T22:00:00+00:00",
      "difference": 0.08499999999999996
    },
    {
      "from_contract": "ZCU26-CBOT",
      "to_contract": "ZCZ26-CBOT",
      "decision_session": "2026-08-17",
      "old_volume": 67263,
      "new_volume": 172743,
      "switch_utc": "2026-08-17T22:00:00+00:00",
      "difference": 0.2475000000000005
    }
  ]
}