condition mean min max ZT0-3 6.75 6.75 6.75 ZT4-7 8.4 8.4 8.4 ZT8-11 8.55 8.55 8.55 ZT12-15 2.8499999999999996 2.8499999999999996 2.8499999999999996 ZT16-19 15.75 15.75 15.75 ZT20-23 7.8 7.8 7.8