Ad rates for big websites decline . The ad rates for big websites have declined over a period of one year, while the rates for small websites have marginally increased.
Compared to the website traffic figures quoted in the above report, my websites are micro and micro micro. But the ad rates I get are 10 to 1000 times higher, since my traffic converts well. Few ad networks (especially those in India , where “good looking” websites are important, not the content of the website) realize this. So till then, one company will continue to dominate internet advertising.