Earth Mean Distance from Sun: 149,597,890 km
Earth Perihelion Distance from Sun: 147,100,000 km
Earth Aphelion Distance from Sun: 152,100,000 km
flux inversely proportional to square of radius
147,100,000 / 152,100,000 = 0.9767
(1/0.9767) * (1/0.9767) = 1.069
or about 7% more
other effects are obviously the angle of entry into the atmosphere of the
sunlight for observer latitude /position of sun in sky, thickness and
effects of the passage of light through atmosphere, ..