condition mean min max ZT0-3 10.087035 8.65945 11.514619999999999 ZT4-7 15.149899999999999 15.149899999999999 15.149899999999999 ZT8-11 15.0238 15.0238 15.0238 ZT12-15 0 0 0 ZT16-19 22.097749999999998 22.097749999999998 22.097749999999998 ZT20-23 17.9037 17.9037 17.9037