condition mean min max ZT0-3 11.154432 11.154432 11.154432 ZT4-7 16.4839225 16.4839225 16.4839225 ZT8-11 15.329259 15.329259 15.329259 ZT12-15 14.740155999999999 14.740155999999999 14.740155999999999 ZT16-19 13.466588 13.466588 13.466588 ZT20-23 12.517381 12.517381 12.517381