condition mean min max ZT0-3 4.299355 4.04666 4.5520499999999995 ZT4-7 5.02641 5.02641 5.02641 ZT8-11 5.57524 5.57524 5.57524 ZT12-15 0 0 0 ZT16-19 9.451035000000001 9.451035000000001 9.451035000000001 ZT20-23 8.950825 8.950825 8.950825