Answer
estimated value: $\$405.5 \text{ billion}$
This is very close to the reported value as it is only $\$0.5 \text{ billion}$ away.
Work Step by Step
The midpoint of these two points is $\dfrac{345+466}{2}=405.5$ (the units are in billions of dollars).
This is extremely close to the reported value of $\$405$ billion.