condition mean min max ZT0-3 2.073655 2.073655 2.073655 ZT4-7 2.65477 2.65477 2.65477 ZT8-11 1.914105 1.914105 1.914105 ZT12-15 2.43921 2.43921 2.43921 ZT16-19 3.12181 3.12181 3.12181 ZT20-23 2.182535 2.182535 2.182535