condition mean min max ZT0-3 5.991156666666667 5.14473 6.956290000000001 ZT4-7 4.68716 4.68716 4.68716 ZT8-11 2.9446849999999998 2.9446849999999998 2.9446849999999998 ZT12-15 7.62213 6.752055 8.492205 ZT16-19 8.07432 8.07432 8.07432 ZT20-23 8.757014999999999 8.757014999999999 8.757014999999999