condition mean min max ZT0-3 7.111515 5.08394 9.13909 ZT4-7 7.1631350000000005 7.1631350000000005 7.1631350000000005 ZT8-11 7.269545 7.269545 7.269545 ZT12-15 0 0 0 ZT16-19 9.89353 9.89353 9.89353 ZT20-23 8.67258 8.67258 8.67258