condition mean min max ZT0-3 6.929225 5.049635 8.808815 ZT4-7 2.27798 2.27798 2.27798 ZT8-11 3.734485 3.734485 3.734485 ZT12-15 0 0 0 ZT16-19 5.96777 5.96777 5.96777 ZT20-23 5.409175 5.409175 5.409175