condition mean min max ZT0-3 520.924364 520.924364 520.924364 ZT4-7 545.042225 545.042225 545.042225 ZT8-11 316.8176395 316.8176395 316.8176395 ZT12-15 257.5868625 257.5868625 257.5868625 ZT16-19 217.78948200000002 217.78948200000002 217.78948200000002 ZT20-23 249.288613 249.288613 249.288613