condition mean min max ZT0-3 7.309376 7.309376 7.309376 ZT4-7 6.16658 6.16658 6.16658 ZT8-11 6.9831465 6.9831465 6.9831465 ZT12-15 7.242585 7.242585 7.242585 ZT16-19 6.6859325 6.6859325 6.6859325 ZT20-23 6.584674 6.584674 6.584674