China's GDP for the first time passed $8 trillion, or about 55 percent the size of the US economy, after the world's second-largest economy struggled to speed up growth in the fourth quarter.

Based on yearly growth of 7.8 percent, the government announced on Friday that the country's 2012 GDP was 51.9 trillion yuan ($8.28 trillion).

GDP grew 7.9 percent in the final quarter, compared with 7.4 percent in the third and 7.6 percent in the second.