condition mean min max ZT0-3 2.199368333333333 2.06744 2.302855 ZT4-7 2.1586350000000003 2.1586350000000003 2.1586350000000003 ZT8-11 1.389625 1.389625 1.389625 ZT12-15 0.9641277500000001 0.7128205 1.215435 ZT16-19 2.07519 2.07519 2.07519 ZT20-23 2.431915 2.431915 2.431915