I'm trying to figure out if some figures put out by Johns Hopkins CARI (China-Africa Research Initiative) in a WaPo piece include (or don't) the so-called "hidden lending" that China supposedly has given. According to some researchers who wrote a NBER paper on this:

Globally, the authors estimate that 50 percent of Chinese foreign lending is not officially recorded by the World Bank’s International Debt Statistics database.

WaPo/CARI claims that (only) 5% of Chinese loans to Africa are interest-free. What does the World Bank say about this? What percentage of China's loans to Africa are interest-free, according to the World Bank?

(I have a good reason to suspect a difference by source on this because e.g. the World Bank's DB says only 12% of Africa's debt it owed to China, but CARI puts that figure at 21%--and I think it's not a typo involved.)