Slower growth in China's value-added industrial output in 2015 has to do with a continued slowdown in traditional heavy sectors, data from the National Bureau of Statistics showed on Tuesday.

An important barometer of overall economic growth, value-added industrial output grew by 6.1 percent year-on-year, 2.2 percentage points slower than 2014.

The growth is mainly being pushed down by overcapacity in traditional heavy industries.