I don't know, but I doubt you will get an answer here - for free - for a number of reasons. I've worked with import/export data so I know some of the vagaries of trying to answer this type of question
1) It's impossible to know an accurate total because statistics are only kept for commodities as they enter and leave the country. If coffee comes on a boat to the Port of Portland and arrives in Seattle by Truck, it will not be included in the data. There is a reverse problem on this for trying to accurately compute our state's export data - when a Boeing airplane stops at Honolulu International Airport for fuel on its way to delivery to a Chinese customer it gets counted as LEAVING the USA from Hawaii. Stats only measure entry and exit points, they don't count INTRAnational transit.
2) Most of these data sets cost a lot of money to access. This one, maintained by the Census bureau costs $200 a pop http://www.census.gov/foreign-trade/reference/products/catalog/impDVD.html I'm curious about your question, but not curious enough to drop $200
3) Setting aside Government data, companies guard their trade secrets. You are going to find that the major players *ahem* *Starbucks* are going to do everything they can to obfuscate the issue, it's not going to be information that any corporation will release publicly.
4) Commodities in government import/export data are usually measured in terms of dollar value, not tonnage. The price of coffee fluctuates on the open market, so there is no easy way to peg it to an aggregate $ figure (even if you COULD find that) to net tonnage.
Sorry to be a Sad Sam on this one, but I highly doubt you're going to be able to find out. It's a great question, but one that would require serious time and a substantial research budget to answer.
But I could be wrong.
Cheers