condition mean min max ZT0-3 12.247929 12.247929 12.247929 ZT4-7 18.1476575 18.1476575 18.1476575 ZT8-11 15.306073000000001 15.306073000000001 15.306073000000001 ZT12-15 14.7233275 14.7233275 14.7233275 ZT16-19 14.97166 14.97166 14.97166 ZT20-23 15.104720499999999 15.104720499999999 15.104720499999999