condition mean min max ZT0-3 4.347386666666667 3.795095 5.059475 ZT4-7 3.333895 3.333895 3.333895 ZT8-11 4.1804250000000005 4.1804250000000005 4.1804250000000005 ZT12-15 5.343725 4.629685 6.057765 ZT16-19 4.77759 4.77759 4.77759 ZT20-23 5.362605 5.362605 5.362605