condition mean min max ZT0-3 3.1182338107499996 2.317521659 3.9189459624999996 ZT4-7 4.553188509249999 3.8019966875 5.304380330999999 ZT8-11 5.264907148000001 4.4635520225 6.0662622735000005 ZT12-15 7.972363175 7.0191675825 8.9255587675 ZT16-19 8.0200108835 6.725409634 9.314612133 ZT20-23 15.73808442 12.46479827 19.01137057