condition mean min max ZT0-3 7.699999999999999 7.699999999999999 7.699999999999999 ZT4-7 6.2 6.2 6.2 ZT8-11 24.85 24.85 24.85 ZT12-15 15.350000000000001 15.350000000000001 15.350000000000001 ZT16-19 19.4 19.4 19.4 ZT20-23 33.4 33.4 33.4