condition mean min max ZT0-3 8.177777779 8.177777779 8.177777779 ZT4-7 6.549444444333333 6.549444444333333 6.549444444333333 ZT8-11 6.08 6.08 6.08 ZT12-15 5.204444444333333 5.204444444333333 5.204444444333333 ZT16-19 4.2811111109999995 4.2811111109999995 4.2811111109999995 ZT20-23 4.848888889 4.848888889 4.848888889