condition mean min max ZT0-3 8.314376666666666 6.444445 10.315965 ZT4-7 5.86303 5.86303 5.86303 ZT8-11 6.213884999999999 6.213884999999999 6.213884999999999 ZT12-15 8.186925 7.884305 8.489545 ZT16-19 8.197564999999999 8.197564999999999 8.197564999999999 ZT20-23 9.855825 9.855825 9.855825