condition mean min max ZT0-3 6.338785 5.0525 7.62507 ZT4-7 5.78329 5.78329 5.78329 ZT8-11 8.3316 8.3316 8.3316 ZT12-15 0 0 0 ZT16-19 15.038499999999999 15.038499999999999 15.038499999999999 ZT20-23 18.89575 18.89575 18.89575