condition mean min max ZT0-3 1.8496833333333333 1.7034099999999999 1.9947000000000001 ZT4-7 3.19201 3.19201 3.19201 ZT8-11 2.9198700000000004 2.9198700000000004 2.9198700000000004 ZT12-15 3.7324450000000002 3.52781 3.93708 ZT16-19 2.68468 2.68468 2.68468 ZT20-23 2.688345 2.688345 2.688345