Unless you do the actual calculation and present why it is off with hundreds of thousands, you cannot say that!
That's quite a different number from the one I posted. If I'm doing my math correctly, 161,000 tons = 5,152,000,000 troy ounces (161,000 * 2,000 (pounds per ton) * 16 (ounces per pound) or 5.15B tons (this number could be rather compromised by the use of troy vs avp pounds and ounces). That's vs the 10 billion troy ounces figure that I posted earlier. I wonder which is the correct figure? I'm also finding data that indicates Palladium is significantly rarer in the earth's crust than Platinum. A 1:15 ratio seems to be repeated often, which seems really odd (especially since a single mine in Russia produces approximately 4x as much Palladium as it does Platinum). Here's some of the source material I found: http://www.outsiderclub.com/report/platinum-and-palladium-more-precious-than-silver-and-gold/935 & https://sg.finance.yahoo.com/news/palladium-basic-facts-investing-tips-135817196.html & http://skeptics.stackexchange.com/q...16-tonnes-of-platinum-in-the-whole-of-history I found another source that seems to have tackled the question by looking at the production records, and that methodology seems more practical (even if it is only current up to 2006): http://www.gold-eagle.com/article/worlds-cumulative-gold-and-silver-production Cumulative Silver Production = 42.97-48.8 billion ounces Cumulative Gold Production = 4.06 - 4.84 billion ounces (for a ratio somewhere between 12.019:1 & 8.878:1) If total Platinum production to date is only 9420 tons (as I've found posted several places without any apparent methodology other than calculating the weight of a cube of the metal of the size that a textbook claimed was total production "in the last 200 years"), or 0.30144 billion ounces (9420 * 2000 * 16). That makes gold's ratio to Platinum something like 1:15 Palladium is quoted (by only a single source I can find, with no methodology or citations) as having a cumulative total of 3,781.5 tons in 2004 & 4,890 tons in 2009: http://www.answers.com/Q/How_much_palladium_has_been_mined_in_human_history#slide=1 Or, between 121,008,000 & 156,480,000 ounces (0.121-0.156 billion cumulative ounces)
You don't need one. Any function would be an approximation in the first place so why not just go directly to the integral approximation from the data.
This is mostly from memory, so might not be 100% correct: I started buying gold and checking out precious metal statistics in the mid-1950's. [My first gold coin was an XF $5 Indian - paid $9.50 for it.] Back then the estimates of the existing world supply was about 2 billion ounces - I remember thinking that was about an ounce per person, world wide.] My Dept. of Commerce book of statistics from that era says total US production through 1956 was about 400 million ounces, which would be about 20% of existing supply - seems reasonable to me. If you add another 60 years at 50 million ounces per year, you get a present supply of about 5 billion ounce - so I tend to go with that number, rather than the 10 billion. But I think the key thing is that whether the supply is increasing at 1 % / year, or 1/2 % / year, it is well under the growth of the world economy, so other things being equal [love that phrase - they never are], the price of gold should continue to increase.
Interesting tidbit I read, At the end of 2011 all the gold ever mined was 171,300 tonnes @ USD $1500 per ounce as of april 2013 the total value of ALL gold ever mined would exceed $USD 8.2 trillion. That would be only a down payment of the US total debt. Scary