condition mean min max ZT0-3 14.338445 14.338445 14.338445 ZT4-7 16.428289 16.428289 16.428289 ZT8-11 12.7925285 12.7925285 12.7925285 ZT12-15 12.747491499999999 12.747491499999999 12.747491499999999 ZT16-19 12.553218999999999 12.553218999999999 12.553218999999999 ZT20-23 12.241628 12.241628 12.241628