condition mean min max ZT0-3 17.613425 14.549 20.67785 ZT4-7 14.19455 14.19455 14.19455 ZT8-11 9.050645 9.050645 9.050645 ZT12-15 0 0 0 ZT16-19 14.3655 14.3655 14.3655 ZT20-23 17.72035 17.72035 17.72035