condition mean min max ZT0-3 9.003127 9.003127 9.003127 ZT4-7 10.198648 10.198648 10.198648 ZT8-11 8.773091999999998 8.773091999999998 8.773091999999998 ZT12-15 9.104970999999999 9.104970999999999 9.104970999999999 ZT16-19 8.6807415 8.6807415 8.6807415 ZT20-23 9.2703165 9.2703165 9.2703165