I checked
all addresses with less than 50,000 sat. The total balance is 18,088.92659937
BTC. That means FreeBitco.in owns 1.266% of all dust.
In total, 22,918,211 addresses hold less than 50,000 sat. Assuming an even distribution, 1.226% puts you at around 290,000 inputs. This is enough to fill about 43 blocks. Assuming my estimate on the number of addresses is correct: consolidating everything at 1 sat/byte would cost 0.43
BTC, which is only 0.19% of the 229
BTC value.
wetsuit just clarified it. The 5% number was completely wrong, most likely a memory lapse on my part.