Developing countries face a series of tough challenges in 2015, including the looming prospect of higher borrowing costs as they adapt to a deepening era of lower prices for oil and other key commodities, resulting in a fourth consecutive year of disappointing economic growth, says the World Bank Group's latest June 2015 Global Economic Prospects (GEP) report. Ayhan Kose, director of Development Prospects, says developing countries expected to grow by 4.4 percent this year.