condition mean min max ZT0-3 1.7373990082499997 0.8579190624999999 2.6168789539999997 ZT4-7 3.2506751654999997 2.7099546996666666 3.7913956313333332 ZT8-11 5.5517481815 5.135394041 5.968102322 ZT12-15 5.6300408565 5.418124241 5.841957472 ZT16-19 9.035858898 7.744582845333333 10.327134950666666 ZT20-23 7.814633519166668 7.520573841666667 8.108693196666668