Does not look like quite half. Looks like about an 1/8th...
I am not familiar with the plane. I am relying on the story:
that half the left wing, containing one fuel tank, was missing.
Reporters get so many things wrong, I wouldn't be too surprised if this were in error. Lessee... (turning to Google)
Cessna 210 wingspan 36' 11''. Missing 5' 7''. Cabin (on a modified plane), about 42''.
Wing length = (36'11'' - 42'')/2 = 200.5''. Missing 67''. It's missing about 28%, or a bit over a quarter.
So you're closer than the reporter, but less dramatic.