presumably this is a low drag v/s lift arrangement (not relying on large angle of attack and extra throttle to keep flying)
You can see that if you want to make lift efficiently, you have to finesse the air a bit, i.e. rely mostly on bernoulli, not on angle of attack.
Here the lift/drag ratio peaks at ~0 degrees angle of attack (which cannot be the zero lift angle in this example then).
Also the coefficient of drag increases exponentially with angle of attack
Max lift coefficient is at about 18 degrees, but the lift/drag ratio is about 8:1 there vs about 22:1 at zero degrees. To create the same amount of lift with the 16 degree angle of attack would take almost 3 times as much power as the 0 degree.