Cirera and Winters (2014) find that aid for trade has a positive impact on exporting and importing times in sub-Saharan African countries, but other factors explain differing experiences in structural change. They find that a 1% increase in aid-for-trade facilitation could generate a USD 415 million increase in global trade. An USAID (2010) evaluation of trade assistance focusing on expansion of exports, trade policy reform, increased participation in trade agreements, and efficiency gains from trade facilitation assistance, finds that each additional US dollar increases the value of developing country exports by USD 42 two years later.