condition mean min max ZT0-3 2.138865 1.687195 2.4770399999999997 ZT4-7 2.09538 2.09538 2.09538 ZT8-11 2.47859 2.47859 2.47859 ZT12-15 3.50061 3.486445 3.514775 ZT16-19 2.551625 2.551625 2.551625 ZT20-23 2.61799 2.61799 2.61799