condition mean min max ZT0-3 2.1975425 2.15788 2.237205 ZT4-7 2.5217650000000003 2.5217650000000003 2.5217650000000003 ZT8-11 2.5293099999999997 2.5293099999999997 2.5293099999999997 ZT12-15 0 0 0 ZT16-19 2.33603 2.33603 2.33603 ZT20-23 2.29253 2.29253 2.29253