condition mean min max ZT0-3 19.415535 19.415535 19.415535 ZT4-7 19.8337445 19.8337445 19.8337445 ZT8-11 18.5777955 18.5777955 18.5777955 ZT12-15 18.350565 18.350565 18.350565 ZT16-19 12.6322505 12.6322505 12.6322505 ZT20-23 12.8609555 12.8609555 12.8609555