EN5329QI efficiency vs Iout experiment

Hi

I built a circuit according to recommended schematic in the datasheet and measured efficiency vs Iout to satisfy the figure in the datasheet.

Conditions;

Ca = 8.6pF,

Cout = 2x22uF

Vin = 5V,

Ra=348.5k ohm ,

Rb= 75k,110, 162k,221k,357k 511k (testing in various Vout).

According to outcomes of the measurements, I create following graphic. And all results includes in the attachment.

There is almost %20 difference on efficiency between my measurements and datasheet.

Do you have any idea about this?