condition mean min max ZT0-3 2.54550574075 1.859732982 3.2312784995 ZT4-7 5.55250154 4.692663547 6.412339533 ZT8-11 8.080222846249999 6.545227034 9.6152186585 ZT12-15 16.5851071425 14.823733105 18.346481179999998 ZT16-19 18.978015324999998 18.141404344999998 19.814626304999997 ZT20-23 23.305291625 22.83188164 23.77870161