condition mean min max ZT0-3 7.397622500000001 7.173675 7.62157 ZT4-7 8.305805 8.305805 8.305805 ZT8-11 8.202425 8.202425 8.202425 ZT12-15 0 0 0 ZT16-19 8.654105000000001 8.654105000000001 8.654105000000001 ZT20-23 8.83375 8.83375 8.83375