condition mean min max ZT0-3 5.95201337025 4.6960050545000005 7.208021686 ZT4-7 7.882663421 7.408817784 8.356509058 ZT8-11 9.416220758 7.8582744295 10.9741670865 ZT12-15 16.45123811 13.90803363 18.99444259 ZT16-19 20.229599415 19.70161925 20.757579579999998 ZT20-23 21.2892094675 20.86291931 21.715499625