condition mean min max ZT0-3 15.487175 14.8134 16.16095 ZT4-7 11.39065 11.39065 11.39065 ZT8-11 15.03145 15.03145 15.03145 ZT12-15 0 0 0 ZT16-19 20.1889 20.1889 20.1889 ZT20-23 14.50975 14.50975 14.50975