condition mean min max ZT0-3 8.22587 8.22587 8.22587 ZT4-7 4.936945 4.936945 4.936945 ZT8-11 4.20625 4.20625 4.20625 ZT12-15 6.41625 6.41625 6.41625 ZT16-19 10.09107 10.09107 10.09107 ZT20-23 10.07293 10.07293 10.07293