condition mean min max ZT0-3 15.691681 15.691681 15.691681 ZT4-7 17.5830335 17.5830335 17.5830335 ZT8-11 20.4569605 20.4569605 20.4569605 ZT12-15 17.668155499999997 17.668155499999997 17.668155499999997 ZT16-19 18.508155000000002 18.508155000000002 18.508155000000002 ZT20-23 20.3405525 20.3405525 20.3405525