condition mean min max ZT0-3 234.820315 234.820315 234.820315 ZT4-7 234.297654 234.297654 234.297654 ZT8-11 278.6805505 278.6805505 278.6805505 ZT12-15 292.338691 292.338691 292.338691 ZT16-19 314.753022 314.753022 314.753022 ZT20-23 217.77977950000002 217.77977950000002 217.77977950000002