condition mean min max ZT0-3 1.2184501666666667 0.6888205000000001 1.662495 ZT4-7 0.6830485 0.6830485 0.6830485 ZT8-11 0.31349899999999997 0.31349899999999997 0.31349899999999997 ZT12-15 0.20417659999999999 0.08157919999999999 0.326774 ZT16-19 0.4833075 0.4833075 0.4833075 ZT20-23 0.8751145 0.8751145 0.8751145