condition mean min max ZT0-3 19.148916 19.148916 19.148916 ZT4-7 16.3083475 16.3083475 16.3083475 ZT8-11 16.4020345 16.4020345 16.4020345 ZT12-15 15.2144945 15.2144945 15.2144945 ZT16-19 16.715108999999998 16.715108999999998 16.715108999999998 ZT20-23 15.889846499999999 15.889846499999999 15.889846499999999