condition mean min max ZT0-3 11.45972 6.08276 14.848700000000001 ZT4-7 6.145525 6.145525 6.145525 ZT8-11 18.1984 18.1984 18.1984 ZT12-15 20.328225 20.28465 20.3718 ZT16-19 20.530050000000003 20.530050000000003 20.530050000000003 ZT20-23 20.50245 20.50245 20.50245