condition mean min max ZT0-3 7.348879 7.348879 7.348879 ZT4-7 7.8657415 7.8657415 7.8657415 ZT8-11 7.5743455 7.5743455 7.5743455 ZT12-15 8.2347935 8.2347935 8.2347935 ZT16-19 8.217727 8.217727 8.217727 ZT20-23 7.9472795000000005 7.9472795000000005 7.9472795000000005