condition mean min max ZT0-3 3.121385 3.00347 3.2393 ZT4-7 3.6150400000000005 3.6150400000000005 3.6150400000000005 ZT8-11 4.0605899999999995 4.0605899999999995 4.0605899999999995 ZT12-15 0 0 0 ZT16-19 4.430775000000001 4.430775000000001 4.430775000000001 ZT20-23 3.96934 3.96934 3.96934