condition mean min max ZT0-3 7.820455 7.820455 7.820455 ZT4-7 9.6436185 9.6436185 9.6436185 ZT8-11 8.956147000000001 8.956147000000001 8.956147000000001 ZT12-15 9.318804499999999 9.318804499999999 9.318804499999999 ZT16-19 9.6973105 9.6973105 9.6973105 ZT20-23 9.5932535 9.5932535 9.5932535