condition mean min max ZT0-3 16.884925 15.0467 18.72315 ZT4-7 10.1292 10.1292 10.1292 ZT8-11 6.60169 6.60169 6.60169 ZT12-15 0 0 0 ZT16-19 17.5298 17.5298 17.5298 ZT20-23 22.4658 22.4658 22.4658