condition mean min max ZT0-3 10.720943333333333 10.720943333333333 10.720943333333333 ZT4-7 6.241265 6.241265 6.241265 ZT8-11 7.3533550000000005 7.3533550000000005 7.3533550000000005 ZT12-15 14.5134 14.5134 14.5134 ZT16-19 21.8461 21.8461 21.8461 ZT20-23 16.6684 16.6684 16.6684