condition mean min max ZT0-3 7.967442 7.967442 7.967442 ZT4-7 8.080452999999999 8.080452999999999 8.080452999999999 ZT8-11 7.1963135 7.1963135 7.1963135 ZT12-15 9.100508 9.100508 9.100508 ZT16-19 7.670018499999999 7.670018499999999 7.670018499999999 ZT20-23 8.4810765 8.4810765 8.4810765