condition mean min max ZT0-3 5.547395 5.547395 5.547395 ZT4-7 3.246245 3.246245 3.246245 ZT8-11 4.60262 4.60262 4.60262 ZT12-15 6.52538 6.52538 6.52538 ZT16-19 7.582925 7.582925 7.582925 ZT20-23 7.134494999999999 7.134494999999999 7.134494999999999