Web usage by iPhone and iPad owners has grown by 35 percent in North American over the past year, while browsing with BlackBerry smartphones and the PlayBook tablet has dropped by 25 percent.

Those Web usage statistics, gathered by mobile ad network Chitika, were offered up in a blog posted Thursday by the company.

The drop in Web use by Research in Motion BlackBerry devices came at the same the company saw a decline in sales. IDC recently said that second quarter 2012 market share for BlackBerry smartphones shipped to retailers dropped to 4.8 percent - a 41 percent decline from the same quarter in 2011.

BlackBerry device Web usage is a small share overall - about 1 percent of all mobile traffic in July 2012. Apple's smartphones and tablets now account for a "staggering" 63 percent of all mobile Web traffic, Chitika said.

Chitika studies Web usage by analysing 250,000 Web sites in North America and regularly looking at hundreds of millions of Web page views of ads each week, a spokesman said.