condition mean min max ZT0-3 1.3750543955 0.8967726509999999 1.8533361400000001 ZT4-7 3.05529302075 2.6391970745 3.471388967 ZT8-11 4.82220007175 3.7753949860000002 5.8690051575 ZT12-15 8.50432359625 7.4165043795 9.592142813 ZT16-19 7.994277544 7.8656574705 8.1228976175 ZT20-23 7.84606336775 7.393136053 8.2989906825