condition mean min max ZT0-3 16.99313244325 13.0849667965 20.90129809 ZT4-7 3.08009626775 2.8611290360000003 3.2990634995 ZT8-11 7.3196874662499996 5.1651856044999995 9.474189328 ZT12-15 9.542311604750001 9.4347809455 9.649842264 ZT16-19 12.824218235 11.8570107 13.79142577 ZT20-23 20.443578795 19.084377335 21.802780255000002