BEIJING, Aug. 15  -- China's affordable housing program is progressing smoothly as construction has begun on 5.17 million units this year, latest data has showed.

The number accounts for around 69 percent of the 7.4 million units planned for the whole year, according to the Ministry of Housing and Urban-Rural Development.

As of the end of July, construction had been nearly completed on 4.25 million units, and a total of 770 billion yuan (120 billion U.S. dollars) had been injected into the program for the January-July period.

Approved in 1999, the program is designed to provide cheaper housing to low-income families who have been edged out by runaway real estate prices.

Over the past four years, more than 20 million affordable houses were completed across the country. The State Council, China's cabinet, has earlier announced a plan to build 18 million apartments in urban areas and renovate 10.6 million rural houses between 2015 and 2017.