condition mean min max ZT0-3 11.907327 11.907327 11.907327 ZT4-7 12.177795 12.177795 12.177795 ZT8-11 15.365162 15.365162 15.365162 ZT12-15 15.768775999999999 15.768775999999999 15.768775999999999 ZT16-19 14.622213 14.622213 14.622213 ZT20-23 19.556555 19.556555 19.556555