condition mean min max ZT0-3 6.53531 6.53531 6.53531 ZT4-7 6.27811 6.27811 6.27811 ZT8-11 5.6491 5.6491 5.6491 ZT12-15 5.431685 5.431685 5.431685 ZT16-19 8.88287 8.88287 8.88287 ZT20-23 7.01294 7.01294 7.01294