condition mean min max ZT0-3 7.217815 7.217815 7.217815 ZT4-7 4.620305 4.620305 4.620305 ZT8-11 5.30894 5.30894 5.30894 ZT12-15 6.604685 6.604685 6.604685 ZT16-19 7.142055 7.142055 7.142055 ZT20-23 7.230705 7.230705 7.230705