condition mean min max ZT0-3 4.365715 3.61431 5.13426 ZT4-7 3.703215 3.703215 3.703215 ZT8-11 2.6354249999999997 2.6354249999999997 2.6354249999999997 ZT12-15 4.49607 3.92535 5.06679 ZT16-19 5.159115 5.159115 5.159115 ZT20-23 6.49283 6.49283 6.49283