I want to ask the following question but I can't figure out the right choice, the answer of the question is in millions of tonnes

**how much potato is harvested each year? 20 tonnes**

or

**how many potatoes are harvested each year? 20 tonnes**

And which sentence would be correct suppose I wanted to talk about a line graph

**The given line graph provides information about how much potato is harvested in millions of tonnes**

or

**The given line graph provides information about how many potatoes are harvested in millions of tonnes**