condition mean min max ZT0-3 8.678648 8.678648 8.678648 ZT4-7 9.166859500000001 9.166859500000001 9.166859500000001 ZT8-11 8.923162999999999 8.923162999999999 8.923162999999999 ZT12-15 8.3929425 8.3929425 8.3929425 ZT16-19 9.009093 9.009093 9.009093 ZT20-23 8.901485 8.901485 8.901485