condition mean min max ZT0-3 7.704385 5.038315000000001 9.452975 ZT4-7 3.59797 3.59797 3.59797 ZT8-11 3.6356349999999997 3.6356349999999997 3.6356349999999997 ZT12-15 6.7538525 6.247775 7.25993 ZT16-19 7.4346 7.4346 7.4346 ZT20-23 10.84145 10.84145 10.84145