Your data is wrong. You estimate 10% of all tests are positive in Luxembourg. That's utter BS. We have tested more poeple than our population and have done multiple testing. The quote is around 1-2% and not 10% as you claim.
This[1] is their source description for Luxembourg. Following their "country profile" link from there, their source seems to be saying around 1% positive test rate for Luxembourg[2].
So it's not clear where the 10.8% figure comes from. I'll try contacting them at their Contact Us email address [3] and see where the difference is coming from.