I am looking at ETFs that track coffee price indices and I have noticed that there is quite big discrepancy between the ETFs underlying coffee indices (Dow Jones-UBS Coffee is an example) and the actual coffee price.
To make it clear, here is the coffee price:
https://www.macrotrends.net/2535/coffee-prices-historical-chart-data
https://www.investing.com/commodities/us-coffee-c

And here is the index price:
https://www.investing.com/indices/dow-jones-ubs-coffee

If you look at the period from 2001 to 2009 the coffee price grew almost 3x while the index dropped by ca. 30%.
Does anybody know where this difference come from. I was thinking that it could be some additional costs to the ETF but the difference seems to big for that.