condition mean min max ZT0-3 3.393498333333333 2.513375 4.15159 ZT4-7 1.624815 1.624815 1.624815 ZT8-11 2.100215 2.100215 2.100215 ZT12-15 1.9390125 1.835405 2.04262 ZT16-19 1.1996799999999999 1.1996799999999999 1.1996799999999999 ZT20-23 1.74337 1.74337 1.74337