condition mean min max ZT0-3 8.194113 8.194113 8.194113 ZT4-7 8.6389315 8.6389315 8.6389315 ZT8-11 9.403587 9.403587 9.403587 ZT12-15 9.843504 9.843504 9.843504 ZT16-19 9.131816 9.131816 9.131816 ZT20-23 8.1847295 8.1847295 8.1847295