Fewer online retailers now have large numbers of affiliates - sites that drive traffic and sales to those retailers' e-commerce sites - but the efficiency of affiliate marketing has increased.

Just 9 percent of retailers now have 10,000 or more affiliates, a significant drop from the 15 percent last year; on the other hand, 37 percent of retailers now have 500 or fewer affiliates, up from last year's 24 percent, writes Internet Retailer, citing the recently released 2007 AffStat Affiliate Marketing Benchmark report.

Despite - or because of - the overall drop in affiliate numbers, however, the return from them has gone up. This year, 15 percent of marketers say conversion rates from affiliates are 5 percent or more - up from 9 percent last year.

Most affiliates, though, deliver 1.6-2.0 percent: 15 percent of marketers reported conversion rates in that range, up only slightly from the previously reported 14 percent.

Editor's note: This item has been updated to reflect the actual results of the AffStat study, rather than the story angle of the Internet Retailer article.