condition mean min max ZT0-3 1.9838933333333335 1.889755 2.1291700000000002 ZT4-7 1.1336785 1.1336785 1.1336785 ZT8-11 1.9298950000000001 1.9298950000000001 1.9298950000000001 ZT12-15 4.5983075 4.22762 4.968995 ZT16-19 2.92158 2.92158 2.92158 ZT20-23 3.771925 3.771925 3.771925