condition mean min max ZT0-3 32.425425 28.759099999999997 36.09175 ZT4-7 12.13815 12.13815 12.13815 ZT8-11 8.856345 8.856345 8.856345 ZT12-15 0 0 0 ZT16-19 23.0018 23.0018 23.0018 ZT20-23 26.19865 26.19865 26.19865