condition mean min max ZT0-3 1.8645266666666667 1.796025 1.91772 ZT4-7 1.675675 1.675675 1.675675 ZT8-11 1.444705 1.444705 1.444705 ZT12-15 2.13097 2.0948350000000002 2.167105 ZT16-19 1.91656 1.91656 1.91656 ZT20-23 2.3069300000000004 2.3069300000000004 2.3069300000000004