condition mean min max ZT0-3 14.958925 12.7074 17.21045 ZT4-7 12.7508 12.7508 12.7508 ZT8-11 14.704450000000001 14.704450000000001 14.704450000000001 ZT12-15 0 0 0 ZT16-19 16.3714 16.3714 16.3714 ZT20-23 11.5141 11.5141 11.5141