condition mean min max ZT0-3 2.792675 2.792675 2.792675 ZT4-7 3.669365 3.669365 3.669365 ZT8-11 5.18186 5.18186 5.18186 ZT12-15 5.417995 5.417995 5.417995 ZT16-19 2.04195 2.04195 2.04195 ZT20-23 1.26906 1.26906 1.26906