interesting birthday statistic?

An old passage in Information is Beautiful shows that horoscopes may not describe anything useful actually.
However, is there something hidden in the birthday data?

Maybe the answer is “yes”.

An interesting “tweet” in Sina Microblog was popularly retweeted. It says: In 2000 in China, population of people in Scorpio is 15.47%, 2 or 3 times of the population of people in other horoscopes.
Why?

The tweet says it is because most people in China make love around Valentine’s Day!

Certainly I want to find some more accurate data. But I failed.
Only one useful tip is that more people are born on October 5 in the United States than any other day, for so many people make love on New Year’s Eve. :-)

It must be an interesting topic of data analysis. Appreciated if anyone can provide ideas or precise data.