Accurate figures exist. In 2016 world gold production was 3,100 metric tons, worth US$128 billion. Above ground gold stock is something over 180,000 metric tons.

New mining increases gold stock 1-2% per year, but very dependent on market conditions.

Gold has double the volatility of equities with less total return than U.S. treasuries. It doesn't really belong in most people's portfolios.