condition mean min max ZT0-3 9.772502 9.772502 9.772502 ZT4-7 9.536089 9.536089 9.536089 ZT8-11 8.7447885 8.7447885 8.7447885 ZT12-15 9.304485499999998 9.304485499999998 9.304485499999998 ZT16-19 9.075429 9.075429 9.075429 ZT20-23 8.920434 8.920434 8.920434