condition mean min max ZT0-3 3.709841666666667 1.50774 4.947205 ZT4-7 2.33541 2.33541 2.33541 ZT8-11 3.441065 3.441065 3.441065 ZT12-15 5.1572525 4.238275 6.07623 ZT16-19 4.58291 4.58291 4.58291 ZT20-23 5.624585 5.624585 5.624585