condition mean min max ZT0-3 15.703833333333334 13.5972 19.6473 ZT4-7 20.6992 20.6992 20.6992 ZT8-11 11.366700000000002 11.366700000000002 11.366700000000002 ZT12-15 4.182487500000001 4.12293 4.242045 ZT16-19 9.504000000000001 9.504000000000001 9.504000000000001 ZT20-23 14.753599999999999 14.753599999999999 14.753599999999999