condition mean min max ZT0-3 8.733635 8.733635 8.733635 ZT4-7 9.1222995 9.1222995 9.1222995 ZT8-11 9.3219525 9.3219525 9.3219525 ZT12-15 8.2408635 8.2408635 8.2408635 ZT16-19 8.81756 8.81756 8.81756 ZT20-23 8.3938305 8.3938305 8.3938305