condition mean min max ZT0-3 8.419881 8.419881 8.419881 ZT4-7 8.3152695 8.3152695 8.3152695 ZT8-11 8.535217 8.535217 8.535217 ZT12-15 7.894366 7.894366 7.894366 ZT16-19 8.412019 8.412019 8.412019 ZT20-23 8.0612215 8.0612215 8.0612215