condition mean min max ZT0-3 33.115892 33.115892 33.115892 ZT4-7 20.043616 20.043616 20.043616 ZT8-11 21.373232 21.373232 21.373232 ZT12-15 14.984138 14.984138 14.984138 ZT16-19 12.777675 12.777675 12.777675 ZT20-23 9.972577000000001 9.972577000000001 9.972577000000001