I've late onset asthma cough variant since 2009. it is under control with inhaler use. my blood test shows 8 percent eisonophilis. is it high?

Eosinophils: Yes, 8% is slightly high, but not extremely so. Typically eosinophils are 5% or less. What was the absolute count? 500 or more is considered elevated. The slightly elevated eosinophil percentage suggests some mild allergic response. Perhaps this is behind your cough-variant asthma. What has your doctor told you?

Slightly: There is a test called FeNO which is used in some Allergy offices. A positive test is a marker for activated eosinophils in the airway. Depending on the frequency and severity of your symptoms, an inhaled steroid may be indicated.