condition mean min max ZT0-3 7.696916 7.696916 7.696916 ZT4-7 7.039566499999999 7.039566499999999 7.039566499999999 ZT8-11 7.5091395 7.5091395 7.5091395 ZT12-15 7.232946999999999 7.232946999999999 7.232946999999999 ZT16-19 7.514383 7.514383 7.514383 ZT20-23 8.6407515 8.6407515 8.6407515