The Internet using population of China topped 253 million according to the Chinese agency tasked with tracking that and other online issues.

The reason why major search engines like Google, Yahoo, and Microsoft held their noses, steeled themselves against negative press, and took their operations into China, censorship requirements be damned.

253 million reasons. And counting.

The BBC cited the China Internet Network Information Center (CNNIC) on the new figure. At 253 million, China has roughly 19 percent of its population online, compared with 223 million in the US, which is 71 percent.

Every time China’s online net population ticks up a percentage point, that’s another 13 million people looking for pop stars, Olympic details, or any other topic against which advertising may be displayed.

Once the spending matches the participation, the search sites will forget anyone ever protested their acquiescence to local censorship requirements, if they haven’t already. The BBC cited Analysys International in declaring China’s Internet economy generating $5.9 billion in revenue in 2007; US companies pulled in $21.2 billion just in online ad revenue.

Local firms to China like Baidu and Sohu won’t give up easily to American firms, and we have to wonder if even Google can surmount the challenge of exceeding those companies in the minds of the Chinese net population. But even incremental success offers a lot of revenue; no one has to win the whole market when a slice is still worth tens or hundreds of millions.