condition mean min max ZT0-3 20.201325 19.94715 20.4555 ZT4-7 11.18868 11.18868 11.18868 ZT8-11 7.645755 7.645755 7.645755 ZT12-15 0 0 0 ZT16-19 13.003319999999999 13.003319999999999 13.003319999999999 ZT20-23 17.4754 17.4754 17.4754