(Wine-Searcher) - The country's most populous states are punching above their weight in buying their wines straight from the source.

Direct-to-consumer wine sales boomed in the U.S. last year, marking growth of more than 15 percent and sales of almost $2 billion, but it's the same people doing the buying.

According to a report compiled by ShipCompliant and Wine & Vine, most of the direct-to-consumer (DTC) wine sales went to the country's five most-populous states; but while California, Texas, New York, Florida and Illinois account for 37 percent of the U.S. population, they swallowed up almost 60 percent of all DTC sales.

Between them, the top five states took 58.5 percent of DTC sales by volume and an even more impressive 61 percent by value. Those figures tie in neatly with figures from Wine Searcher's database that show more than half of all U.S. searches come from those five states.

However, the other 45 states are starting to pull a little more weight, too. Shipments to Montana grew by 245 percent after that state's legislature fixed its direct shipping law to allow wineries to obtain shipping permits, rather than rely on the unworkable "Connoisseurs Licenses" used to track direct shipments previously.

North Dakota legislators also made it easier to ship wine into the state, resulting in a 61 percent increase in shipments.

Overall, DTC sales (which do not include wine shipped by retailers or wine carried out of wineries by consumers) rose by 13 percent. A total of 3.95 million cases were sold direct in 2014. The value of DTC sales was $1.82bn, a rise of 15.5 percent on last year, or four times the rate of growth of traditional sales channels for the same period.

It is no surprise California ships the most wine direct, with 81.3 percent, but it is Oregon that has emerged as a star performer this year, with wine shipments growing by 46.3 to more than 183,000 cases, bringing in $87.5m, a rise of 52.5 percent on last year. Napa alone accounted for 32 percent of total volume of direct wine sales and 48.5 percent of sales by value, an increase of 12.2 percent on 2013.

When it comes to grape varieties, Cabernet is still king, topping both the volume and value charts and carrying an average price of $66.32 a bottle, up 4.3 percent on last year. However, Pinot Noir was the breakout success, growing 21.8 percent by volume and a whopping 33.1 percent by value, to end up with the second best average price of $45.28.