condition mean min max ZT0-3 15.664337 15.664337 15.664337 ZT4-7 18.0570915 18.0570915 18.0570915 ZT8-11 17.861383500000002 17.861383500000002 17.861383500000002 ZT12-15 15.914852 15.914852 15.914852 ZT16-19 23.015102499999998 23.015102499999998 23.015102499999998 ZT20-23 19.212971 19.212971 19.212971