condition mean min max ZT0-3 2.658575 1.781685 3.535465 ZT4-7 1.728035 1.728035 1.728035 ZT8-11 0.5736355 0.5736355 0.5736355 ZT12-15 0 0 0 ZT16-19 1.778865 1.778865 1.778865 ZT20-23 2.44092 2.44092 2.44092