condition mean min max ZT0-3 0.9930766666666666 0.558951 1.7279049999999998 ZT4-7 1.1857600000000001 1.1857600000000001 1.1857600000000001 ZT8-11 1.2264445 1.2264445 1.2264445 ZT12-15 0.7612245 0.570326 0.952123 ZT16-19 0.725703 0.725703 0.725703 ZT20-23 0.4661165 0.4661165 0.4661165