With the end of the holiday season approaching, online retail spending continues to hit record highs, comScore (NASDAQ:SCOR) reported this week.

More than $20 billion has been spent online so far this holiday season, up 19 percent from 2006, according to the Virginia-based data collection firm.

On "Green Monday" -- a term coined by eBay (NASDAQ:EBAY) to describe the second Monday in December, which the company says is the heaviest online spending day of the year -- U.S. online spending reached $881 million, the highest one-day total in history.

"Consumers are clearly responding positively to the enticing promotions and discounts being offered by retailers this year," comScore chairman Gian Fulgoni said in a statement. "Spending is currently on track to meet our forecast of $29.5 billion for the season."