NEW YORK - Americans spent more on items such as furniture during the holidays this year, with online shopping, in particular, seeing a big spike, according to a report released Monday.

Overall spending rose 7.9 percent from a year ago, according to the MasterCard SpendingPulse report, which tracks retail sales across cards, cash and checks from Black Friday to Christmas Eve.

The uptick was driven by people sitting in the comfort of their homes or at work, with online shopping up 20 percent.

Online retail giant Amazon said Monday that its $99-a-year Prime loyalty program that includes unlimited free two-day shipping gained three million new members in the third week of December alone. Meanwhile, the number of Prime members shopping by mobile more than doubled this holiday season, the Seattle-based Amazon said.

Christmas Eve was the biggest day yet for deliveries by the company's Prime Now service, which offers free two-hour delivery to more than 20 metropolitan areas. When Prime Now launched last year, it delivered only within Manhattan.

Amazon also said it shipped a record number of items worldwide for the holidays, with items going to 185 countries.

Shopping at physical stores still accounts for the majority of spending during the holidays. But the continuing shift to online shopping is forcing retailers to improve their websites, or offer perks such as faster or free delivery.

Earlier this month, another report, by First Data, also found that online sales growth was outpacing sales growth at physical stores. That report was based on payments from Oct. 31 to Dec. 14.

The SpendingPulse report does not include spending by dollar amounts. But the National Retail Federation, the nation's largest retail trade group, expects sales for November and December to rise 3.7 percent to $630.5 billion from a year ago.

For the traditional holiday shopping period from Black Friday to Christmas Eve, the MasterCard SpendingPulse report found that furniture sales rose in the double-digit percentages, indicating that people are comfortable spending on big-ticket wares.

Sales of women's clothing also rose by double digits, while sales of men's apparel declined. The report noted that the warm weather this fall pushed back sales of clothing, leading to some pent-up demand during the holiday shopping period. Retailers such as Macy's had said the unseasonably warm temperatures would force it to slash prices on items such as coats and boots during the holidays.

The SpendingPulse report is based on sales activity on the MasterCard payments network, along with estimates for cash and check spending based on surveys.