condition mean min max ZT0-3 8.860686 8.860686 8.860686 ZT4-7 9.7344535 9.7344535 9.7344535 ZT8-11 7.502196 7.502196 7.502196 ZT12-15 7.8076384999999995 7.8076384999999995 7.8076384999999995 ZT16-19 7.747184 7.747184 7.747184 ZT20-23 8.37895 8.37895 8.37895