condition mean min max ZT0-3 8.705415 8.000805 9.410025000000001 ZT4-7 6.696755 6.696755 6.696755 ZT8-11 8.992014999999999 8.992014999999999 8.992014999999999 ZT12-15 0 0 0 ZT16-19 8.750150000000001 8.750150000000001 8.750150000000001 ZT20-23 8.5961 8.5961 8.5961