condition mean min max ZT0-3 11.9413 11.9413 11.9413 ZT4-7 8.25084 8.25084 8.25084 ZT8-11 4.4097100000000005 4.4097100000000005 4.4097100000000005 ZT12-15 6.03074 6.03074 6.03074 ZT16-19 7.20528 7.20528 7.20528 ZT20-23 8.979005 8.979005 8.979005