condition mean min max ZT0-3 5.56588 5.56588 5.56588 ZT4-7 4.1749149999999995 4.1749149999999995 4.1749149999999995 ZT8-11 3.1076716666666666 3.1076716666666666 3.1076716666666666 ZT12-15 3.6849600000000002 3.6849600000000002 3.6849600000000002 ZT16-19 4.12765 4.12765 4.12765 ZT20-23 2.443715 2.443715 2.443715