condition mean min max ZT0-3 6.985008333333333 3.520045 8.952335 ZT4-7 3.16147 3.16147 3.16147 ZT8-11 3.91604 3.91604 3.91604 ZT12-15 5.8292425 5.14555 6.512935000000001 ZT16-19 6.920925 6.920925 6.920925 ZT20-23 9.96813 9.96813 9.96813