condition mean min max ZT0-3 8.87683 8.87683 8.87683 ZT4-7 7.26025 7.26025 7.26025 ZT8-11 6.17797 6.17797 6.17797 ZT12-15 7.29308 7.29308 7.29308 ZT16-19 8.622225 8.622225 8.622225 ZT20-23 7.91236 7.91236 7.91236