With every passing month, mobile commerce is taking over more and more of online retailing. Witness the latest figures from Affiliate Window, which operates affiliate networks in the U.S. and the U.K. Sales via smartphones and tablets through the networks accounted for 19.0% of total web sales in May 2013 and 30.6% in May 2014, Affiliate Window reports.

What’s more, traffic from both smartphones and tablets continues to grow at the expense of desktops, which are losing favor among online shoppers, many studies show. In May 2013, 71.4% of total traffic on the affiliate networks stemmed from desktops, 11.4% from smartphones, 11.4% from tablets and 5.8% from other devices (mainly feature phones and game consoles), Affiliate Window says. But in May 2014, desktop traffic was down to 63.7% while smartphone traffic was up to 17.4%, tablet traffic was up to 14.8% and other device traffic was down to 4.1%.

Similarly, 62% of time spent with online retail in the U.S. in April 2014 occurred on mobile devices, up from 55% in July 2013, web and mobile measurement firm comScore Inc. reports.

The Affiliate Window study of May 2014 commerce activity on its networks also finds that:

• 25% of total revenue came from mobile shoppers.
• Apple iPhones accounted for 75.0% of smartphone traffic and 75.1% of smartphone sales while Android smartphones accounted for 25.0% of traffic and 24.9% of sales.
• Apple iPads accounted for 72.6% of tablet traffic and 84.1% of tablet sales while Android tablets accounted for 27.4% of tablet traffic but only 15.9% of tablet sales.
• Tablet shoppers converted at a rate of 6.0% while smartphone shoppers converted at a rate of 2.9%. The average mobile conversion rate was 4.1%.
• 23,000 sales each day originated from a mobile device: 14,750 on tablets and 8,250 on smartphones.
• 387 clicks originated from a mobile device every minute.
• 343 sales were generated through a smartphone each hour.

Mobile shoppers on affiliate networks convert at higher rates than mobile shoppers overall for a variety of reasons, says Matt Swan, client strategist at Affiliate Window.

“High conversions rates are typical for the types of promotions we see perform well through mobile,” Swan says. “For example, incentivized traffic—cash back, voucher codes—has always converted extremely well and it typically overindexes in mobile commerce. Additionally, the products we see convert well through mobile are typically lower value items.”

Follow Bill Siwicki, managing editor, mobile commerce, at Internet Retailer, at @IRmcommerce.