Nobody should pay any attention to the metric because it's a silly way to value a company. Think about it: there are about 7 billion pairs of eyeballs, ignoring maybe 1% who are legally blind and/or Braille ads do not exist. 110/7 => Google revenue is generating $15.7 per viewer per year. And Google expects people to believe that this value will increase each year, when the denominator is increasing and the numerator is decreasing due to competition.

Viewed as an advertiser (Google's real customers), I would like this number to come down over time.