Telecoms accounted for 13% of online ad impressions in May 2005, up from 8% in May 2004, Nielsen//NetRatings reports. Web media ads accounted for 20% of all May impressions, down from 22% in May 2004. Financial service marketers were responsible for 18% of all online impressions, compared to 19% in May 2004. Retailers accounted for 14% of online ads, down from 15% in May 2004. Marketers across a variety of industries delivered 93.1 billion impressions in May 2005, up from 91.4 billion in April 2005, but still down from the 97.1 billion served in March 2005.