condition mean min max ZT0-3 6.542797 6.542797 6.542797 ZT4-7 7.4764 7.4764 7.4764 ZT8-11 8.4419215 8.4419215 8.4419215 ZT12-15 8.379352 8.379352 8.379352 ZT16-19 8.3853895 8.3853895 8.3853895 ZT20-23 7.554363 7.554363 7.554363