condition mean min max ZT0-3 8.269285 8.10631 8.43226 ZT4-7 5.666295 5.666295 5.666295 ZT8-11 6.48015 6.48015 6.48015 ZT12-15 0 0 0 ZT16-19 7.87106 7.87106 7.87106 ZT20-23 6.34851 6.34851 6.34851