Paid search generated 20.3% for retailers from back-to-school and Labor Day purchases online, trailing behind direct traffic to retail websites at 25.1% and email at 30.1%, according to data released Thursday.

Data from Adobe Digital Insights (ADI) suggests that organic search came in at No. 4 with 19.6%, followed by referral traffic at 2.9%, social networks at 1.2%, and display at 0.8%.

Overall, consumers still prefer to make purchases from a desktop. Some 40% say their smartphone’s screen is too small, 34% report that the mobile website and app are difficult to navigate and 24% said both lack full functions to do rapid checkout.

Back-to-school shopping topped earlier predictions by ADI, reaching $58.1 billion for the 2018 season.

“Four out of 10 said they would just stay home and not even go to a physical store,” said. Michael Klein, director of industry strategy for retail and travel and hospitality for Adobe.

The data also predicts that online shopping growth will continue into the holiday season, and the retailers performing strongly in the beginning of 2018 will perform best.

Data released Thursday from ADI found that $38.5 billion came from desktops between July 23 and Septenber 5, 2018, with purchases converting at 3.37% and average basket size of $142.

Consumers spent 25% —  a total of $14.5 billion — through smartphone devices, with a conversion rate of 1.24% and average order value of $111. Tablets helped to generate $5.1 billion in online purchases, with a conversion rate of 2.34% and an order value of $125.

Labor Day became the first holiday to reach $2.08 billion — up 23.4% from the prior year — aside from the holiday season from November through December. Holiday sales were driven by expensive items, per the data, such as electronics, appliance and home and garden products such as mattresses and grills.

Consumers spent more money through smartphones on Labor Day in 2018, compared with back-to-school. Spend reached 28.4%, compared with 25% for back-to-school.

In 2017, smartphones during back-to-school generated 20.5% of revenue share, rising to 25% in 2018. Smartphones appeared to take share from desktops and tablets, while desktops generated nearly 70% of the revenue share in 2017, declining to 66.2% in 2018. Tablets experienced the same drop from 9.7% in 2017 to 8.8% in 2018.

Labor Day has the same influence on revenue. Smartphones drove 22.2% of revenue in 2017, up to 28.4% in 2018. Desktops generated 65.8% in 2017 — falling to 60.9% in 2018 — and tablets generated 12% in 2017, falling to 10.7% in 2018.