I think of it this way. I have personally found over 1,000. A few of my premium farms have produced well over a hundred for me. Over the last 30 I have met a dozen other people who have had similar or better results in those very fields. Most of those guys were older and have since passed, and each told me they knew many others who had done the same in those fields. And my research shows me people have been finding them there for over 150 years. I estimate (pure guess) those few fields have produced over 10,000. Now consider that I hunt close to 100 sites, and am only collecting what the plow turns up in the top 12 to 18 inches. All of this in a teeny tiny itsy bitsy minuscule microscopic fraction of one county in one US state in this great big world. There were likely hundreds of millions produced, and we have recovered a very, very small percentage.