A report released late last week finds that, beginning in 2015, just over half (50.1 percent) of spending on paid search ads will go towards mobile ads. The findings come from research firm eMarketer, who also predicts the trend to continue until mobile claims 76.7 percent of US search ad spend in 2018.

These findings show the swift and clearly defined shift in ad spend, as less than a quarter (24.7 percent) of search spending went to mobile only last year.

The report says the change is the result of “the ubiquity of smartphones, and consumers’ growing use of phones in almost every waking moment of the day,” which in itself “means that search will be more mobile than desktop next year.”

While more spending is going to mobile, ROI is not quite following. The report does predict mobile ROI will continue to improve, but it will continue to trail desktop ROI until tracking and analysis becomes more precise and marketers can further refine their efforts.