condition mean min max ZT0-3 6.95887 5.339145 8.477975 ZT4-7 5.21614 5.21614 5.21614 ZT8-11 5.307945 5.307945 5.307945 ZT12-15 7.7873325 6.797124999999999 8.77754 ZT16-19 6.452859999999999 6.452859999999999 6.452859999999999 ZT20-23 8.556275 8.556275 8.556275