condition mean min max ZT0-3 7.366825 7.366825 7.366825 ZT4-7 7.6255489999999995 7.6255489999999995 7.6255489999999995 ZT8-11 7.2779905 7.2779905 7.2779905 ZT12-15 8.085245 8.085245 8.085245 ZT16-19 7.3216090000000005 7.3216090000000005 7.3216090000000005 ZT20-23 7.997959999999999 7.997959999999999 7.997959999999999