As China pins its hopes for boosting consumer demand on growth in the number of urban residents, an ominous sign looms large: The pace of urbanization in the world's most populous country is slowing.

According to the latest data from the National Bureau of Statistics, China added 19.29 million people to the urban population in 2013. This seemed impressive, but it was lower than the 21.03 million new urban residents seen in 2012.

From 2008 to 2013, the urbanization rate of the country climbed from 45.7 percent to 53.7 percent. But the annual gain was smaller each year. In 2010, there was a 3.35 percentage point gain, the highest annual increase. The gain dropped by 1.3 percentage points in 2012 and then by another 1.16 percentage points last year.