condition mean min max ZT0-3 18.083636 18.083636 18.083636 ZT4-7 16.486214 16.486214 16.486214 ZT8-11 19.6081055 19.6081055 19.6081055 ZT12-15 18.960433000000002 18.960433000000002 18.960433000000002 ZT16-19 18.012158499999998 18.012158499999998 18.012158499999998 ZT20-23 18.02955 18.02955 18.02955