condition mean min max ZT0-3 7.439216666666667 5.97922 8.675725 ZT4-7 6.2218350000000004 6.2218350000000004 6.2218350000000004 ZT8-11 7.889620000000001 7.889620000000001 7.889620000000001 ZT12-15 13.602825 12.60985 14.5958 ZT16-19 10.733985 10.733985 10.733985 ZT20-23 10.9945 10.9945 10.9945