condition mean min max ZT0-3 20.905275 20.33885 21.4717 ZT4-7 19.255899999999997 19.255899999999997 19.255899999999997 ZT8-11 20.02055 20.02055 20.02055 ZT12-15 0 0 0 ZT16-19 25.2262 25.2262 25.2262 ZT20-23 22.9485 22.9485 22.9485