condition mean min max ZT0-3 4.880305 4.880305 4.880305 ZT4-7 1.892395 1.892395 1.892395 ZT8-11 3.3928700000000003 3.3928700000000003 3.3928700000000003 ZT12-15 4.490465 4.490465 4.490465 ZT16-19 6.872785 6.872785 6.872785 ZT20-23 6.460395 6.460395 6.460395