The amount of money consumers spend online is expected to increase 75 percent by 2010, with the Internet influencing nearly half of all U.S. retail sales, a market research firm said Monday.

U.S. consumers are expected to spend $144 billion in 2010 from $81 billion last year, JupiterResearch said. Spending this year is expected to reach $95 billion.

By 2010, 71 percent of online people will use the Internet to shop, compared with 65 percent last year. The small increase indicates that retailers will mostly be dealing with an experienced population of online shoppers who are savvy about finding free shipping and deeper discounts, the research firm said.

The Internet is expected to influence nearly half of retail sales in 2010, compared with 27 percent last year. The projection is based on a combination of total sales online with those carried off line, but encouraged by online research. Driving the expected growth were the 85 percent of online shoppers who said they used the Internet to research their offline purchases last year.

"The fact that the Internet will influence nearly half of total retail sales in 2010 is a staggering statistic for a shopping channel that will have been around for little more than 15 years by 2010," JupiterResearch analyst David Schatsky said in a statement. "Our research shows that this presents an enormous opportunity for retailers that embrace a well-integrated multi-channel operational strategy."