condition mean min max ZT0-3 8.976704 8.976704 8.976704 ZT4-7 9.078299999999999 9.078299999999999 9.078299999999999 ZT8-11 8.7576985 8.7576985 8.7576985 ZT12-15 8.520724000000001 8.520724000000001 8.520724000000001 ZT16-19 7.2476590000000005 7.2476590000000005 7.2476590000000005 ZT20-23 6.63068 6.63068 6.63068