condition mean min max ZT0-3 8.562187 8.562187 8.562187 ZT4-7 9.7432935 9.7432935 9.7432935 ZT8-11 8.391014 8.391014 8.391014 ZT12-15 7.7058425 7.7058425 7.7058425 ZT16-19 8.2026735 8.2026735 8.2026735 ZT20-23 8.6223665 8.6223665 8.6223665