Total revenue at Amazon topped $100 billion in 2015, hitting $107.0 billion. The jump makes for a 20% increase in sales, over 2014.

Excluding the negative impact of foreign currency exchange, sales were up 26%. The company also reported a dramatic gain in operating income, which rose to $2.2 billion in the year, from $178 million in 2014. Net income was $596 million, compared to a loss of $241 million in 2014.

Despite the solid numbers for the full year, investors were worried about the fourth quarter in which Amazon posted large gains in sales and earnings, but profits failed to hit analysts’ targets.

The company’s full year earnings were boosted by Amazon Web Services (AWS), its cloud computing division that had sales of $7.9 billion in 2015 and operating income of $1.9 billion. Amazon’s North America group had operating income of $2.7 billion, but its international group had an operating loss of $91 million.

In its North America media group, which includes all book sales, revenue rose 8% in the year, to $12.5 billion. Sales in the international media group fell 8%, due in part of unfavorable exchange rates.

In the call with analysts discussing the results, Amazon executives (which did not include CEO Jeff Bezos) said they will continue to invest in the business, while also looking for operating efficiencies. The three major areas of investment, executives said, are Prime, fulfillment centers, and AWS. Prime Now, Amazon's one-hour delivery option, is in over 25 markets and will be expanded this year. The company closed 2015 with 123 fulfillment centers and executives acknowledged that during the holiday season its warehouses were packed due in part to a big increase in its Fulfillment By Amazon business. AWS is on track to become a $10 billion business.

For the first quarter of 2016, Amazon said it expects revenue to increase between 17% and 28% over the first quarter of 2015 with operating income between $100 million and $700 million compared to income of $255 million in last year’s first period.

This story was updated to include news from the analysts conference call.