condition mean min max ZT0-3 15.771448 15.771448 15.771448 ZT4-7 12.653246 12.653246 12.653246 ZT8-11 17.0934205 17.0934205 17.0934205 ZT12-15 14.2769055 14.2769055 14.2769055 ZT16-19 18.073531 18.073531 18.073531 ZT20-23 14.0857505 14.0857505 14.0857505