condition mean min max ZT0-3 22.068275 19.5043 24.63225 ZT4-7 15.52855 15.52855 15.52855 ZT8-11 11.9357 11.9357 11.9357 ZT12-15 0 0 0 ZT16-19 30.098550000000003 30.098550000000003 30.098550000000003 ZT20-23 25.878 25.878 25.878