condition mean min max ZT0-3 12.508666666666667 6.978249999999999 16.57815 ZT4-7 8.296 8.296 8.296 ZT8-11 7.80854 7.80854 7.80854 ZT12-15 9.6773575 8.779735 10.57498 ZT16-19 12.1481 12.1481 12.1481 ZT20-23 18.54705 18.54705 18.54705