0.003% yield rate

From Days of Sadness, Years of Triumph by Geoffrey Perrett.

Certainly this was a mechanically minded generation already. The country boasted millions of hobbyists, tinkerers and inventors. No sooner had the war begun than an old standby, the "death ray," was revived. One inventor, a Cleveland physician, claimed to have obliterated a pigeon on the wing at a distance of four miles. In the months since then, Washington offices had been deluged with proposals, addressed to everyone from the President to "Boss of Guns, U.S. Navy," for military inventions. Yet in the First World War more than 100,000 ideas had yielded only three devices which proved practicable, and nothing so far appeared likely to threaten that record.

Enthusiasm is important and often necessary but never a substitute on its own for informed purposefulness.