The proportion of the population holding urban household registration, or hukou, increased from 35.93 percent in 2013 to 44.38 percent toward the end of last year, the Ministry of Public Security said on Wednesday.

That means more than 100 million rural residents became urban residents during the six-year period thanks to the government's hukou reforms to allow farmers-turned-migrant workers to apply for urban hukou in all small and medium-sized cities.

However, it is still difficult for farmers to apply for hukou in big cities, where education, medical care, pensions and other kinds of basic public services are much better than those offered in the smaller cities.

That means there are many challenges facing the hukou system reform. The reformers need to bear in mind the purpose is not to "urbanize" farmers, but to shorten the gap between villages and cities in terms of infrastructure, basic public services and the protection of residents' legal rights, particularly property rights.

Yet given the scale at which public resources and production factors are being concentrated in big cities, particularly megacities such as Beijing, Shanghai, Shenzhen and Guangzhou, the vast rural areas will continue to hollow out as farmers prefer to work as migrant workers in these cities without urban hukou and local public services.

Also, the hukou reform should not create a one-way population flow but grant the people the freedom to pursue better lives wherever they want. Urban residents should also be allowed to invest in and relocate to rural areas.

As such, the purpose of the hukou reform should be to do away with the system that divides people into rural and urban camps the moment they are born, and treats them accordingly.

Admittedly, scrapping the system would be a step-by-step process as the country should allocate more resources to modernize agriculture and the rural areas, and have enough means to provide equal basic public services to its citizens wherever they are born.