condition mean min max ZT0-3 2.411229714 2.323125908 2.49933352 ZT4-7 1.4041710505 1.353873093 1.454469008 ZT8-11 1.1377022987499998 1.0842201885 1.1911844089999999 ZT12-15 2.4046252527500003 1.632799382 3.1764511235000006 ZT16-19 3.2474897612499998 3.0910530705 3.403926452 ZT20-23 5.771029264 5.1061812584999995 6.435877269500001