On Fri, 11 Nov 2016, Ed LeBouthillier wrote:
Let's have some respect for the numbers here -- it was nowhere near that.
NASA's entire budget for the two or three peak years of Apollo (and it was
quite a sharp peak) was about 5% of the Federal budget, and a much smaller
percentage of GDP.
That figure is more of a reflection of statements that I've heard on the matter than on any personal research.