condition mean min max ZT0-3 30.70068894 21.67518578 39.7261921 ZT4-7 49.0207831875 46.003514045 52.03805233 ZT8-11 73.36309260750001 65.546063755 81.18012146000001 ZT12-15 39.4840480225 26.126333765 52.84176228 ZT16-19 16.6692088075 13.521929405 19.81648821 ZT20-23 11.30337675975 10.1074503795 12.49930314