Adult Internet users now spend an average of 13 hours online each week and the poor economy is a big reason why.

That’s according to a new Harris Interactive poll, which found a “striking” increase in the amount of time spent online over the last two years, compared to all previous years.

The jump likely stems from greater Internet access in the United States, Harris said, as well as more sites to visit, applications to use and the ability to watch TV online. More than anything, however, “hours online may have increased because of the recession,” Harris said in a press release. “Going online is free; going out usually costs money.”

Keep in mind that 13 hours is just the average – Harris experts said 20 percent of people polled surf the Web for only two hours or less per week, while 14 percent spend at least 24 hours online every week. The latter group tends to range in age from 30 to 39 years old.

And yet, while the recession bears much of the weight for this higher usage, going online is not necessarily a way to avoid spending money – half of Internet users bought something online in the last month.