But you have to remember that the surface of the balloon, which looks like a spherical shell here, is actually three dimensionalour 3-dimensional universe, not a 2D surface. That's why they call it a hypersphere.
The fraction is .0000376.
.0000376 x 1,883,652 Km = 70.4 Km Ofof new space every second for the Megaparsec.
When you consider the slight uncertainties in the numbersdistances, It'sit's correct to within 0.25%. The exact numbers are here.