huju, thanks, I don’t think this is a full estimate. See my discussion above. I looked CJR 2008 review – for CPB, it also has 14% universities, 10% foundations, and 21% business. Another chart for NPR is is similar – 40% is programming fees coming from local stations that are also subsidized. Each of these groups have a lot of public funds involved.
Here is what is purely private for NPR: 1% membership dues, and maybe 20% sponsorship although this can also be in part from public sources.