condition mean min max ZT0-3 7.34 7.34 7.34 ZT4-7 6.9 6.9 6.9 ZT8-11 9.279999999000001 9.279999999000001 9.279999999000001 ZT12-15 5.187777777666667 5.187777777666667 5.187777777666667 ZT16-19 4.684444444333334 4.684444444333334 4.684444444333334 ZT20-23 4.841111111 4.841111111 4.841111111