condition mean min max ZT0-3 36.736731 36.736731 36.736731 ZT4-7 23.945296 23.945296 23.945296 ZT8-11 20.189946 20.189946 20.189946 ZT12-15 18.9802705 18.9802705 18.9802705 ZT16-19 18.017100999999997 18.017100999999997 18.017100999999997 ZT20-23 17.490541 17.490541 17.490541