condition mean min max ZT0-3 18.556413 18.556413 18.556413 ZT4-7 18.662697 18.662697 18.662697 ZT8-11 20.08309 20.08309 20.08309 ZT12-15 17.216935 17.216935 17.216935 ZT16-19 23.540823000000003 23.540823000000003 23.540823000000003 ZT20-23 20.317411999999997 20.317411999999997 20.317411999999997