condition mean min max ZT0-3 4.613135 3.8383450000000003 5.387925 ZT4-7 3.9552 3.9552 3.9552 ZT8-11 5.43895 5.43895 5.43895 ZT12-15 0 0 0 ZT16-19 16.9711 16.9711 16.9711 ZT20-23 10.520125 10.520125 10.520125