condition mean min max ZT0-3 19.404105 19.404105 19.404105 ZT4-7 11.509628 11.509628 11.509628 ZT8-11 9.737237499999999 9.737237499999999 9.737237499999999 ZT12-15 9.988178999999999 9.988178999999999 9.988178999999999 ZT16-19 9.4241925 9.4241925 9.4241925 ZT20-23 9.8245295 9.8245295 9.8245295