condition mean min max ZT0-3 6.384685 5.97149 6.79788 ZT4-7 5.36708 5.36708 5.36708 ZT8-11 14.05585 14.05585 14.05585 ZT12-15 0 0 0 ZT16-19 18.691000000000003 18.691000000000003 18.691000000000003 ZT20-23 10.739965000000002 10.739965000000002 10.739965000000002