condition mean min max ZT0-3 8.440623 8.440623 8.440623 ZT4-7 8.833517 8.833517 8.833517 ZT8-11 10.1021885 10.1021885 10.1021885 ZT12-15 9.6445555 9.6445555 9.6445555 ZT16-19 10.162537 10.162537 10.162537 ZT20-23 9.018972 9.018972 9.018972