condition mean min max ZT0-3 14.84685 14.84685 14.84685 ZT4-7 8.263385 8.263385 8.263385 ZT8-11 8.123365 8.123365 8.123365 ZT12-15 9.6475 9.6475 9.6475 ZT16-19 20.617849999999997 20.617849999999997 20.617849999999997 ZT20-23 16.69695 16.69695 16.69695