Rwanda has also illegally exploited Congolese minerals, which is an important aspect of the success of Rwanda's economy. Political economy researcher Stefaan Marysse estimated that in 1999, 6.1 % of Rwanda’s GDP came from illegal resource extraction in the DRC. In 2013, foreign aid made up over 20 percent of GDP and nearly half of the budget. Economic growth has disproportionally accrued to elites in the capital while rural areas lag behind. Although the government officially has a policy of privatization, in practice it has increased state control of the economy using corporations with strong ties to the state and the ruling party.