A calculated measurement in which the number of eosinophil granulocytes is divided by the number of all white blood cells in a specified sample of peripheral venous blood, and the result presented as a ratio, fraction, quotient or percentage. An eosinophil is a granular leukocyte having a nucleus with two lobes connected by a thread of chromatin, and cytoplasm containing coarse, round granules of uniform size that stain readily with eosin and other acid dyes. The trait is eosinophil percentage of leukocytes (EFO_0007991, an Experimental Factor Ontology term). Also known as: blood eosinophil count to total leukocyte count ratio, eosinophil count as percentage of total white blood cells, eosinophil count to total WBC count ratio, eosinophil percentage, eosinophil percentage of white cells.