condition mean min max ZT0-3 29.134266 29.134266 29.134266 ZT4-7 26.0724935 26.0724935 26.0724935 ZT8-11 22.286126 22.286126 22.286126 ZT12-15 22.8762775 22.8762775 22.8762775 ZT16-19 21.643947500000003 21.643947500000003 21.643947500000003 ZT20-23 22.569070500000002 22.569070500000002 22.569070500000002