Nine more developing economies became dependent on commodity exports between 2010 and 2015, bringing the total to 91, about two-thirds of all the 135 developing countries, a new UN report says.

The report shows that, during the same period, developing countries saw their revenue from commodity exports jump 25 percent to $2.55 trillion.

Commodity dependence can negatively affect human development indicators like life expectancy, education, and per capita income, and about two thirds of commodity-dependent developing countries recorded a low or medium human development index in 2014-2015, according to the report, “The State of Commodity Dependence 2016.”

“In the context of dramatic volatility in commodity prices, developing countries will struggle to achieve the Sustainable Development Goals unless they break the chains of commodity dependence,” UNCTAD Secretary-General Mukhisa Kituyi said in Geneva ahead of the report’s release. “Many developing countries have been commodity-dependent for the past three decades, and it is worrying to see that the numbers are going up.”

The rise in commodity dependence was most noticeable in Africa, where seven new countries entered the category in 2014-2015, bringing the total to 46. Over the same period, the number remained stable at 28 in Latin America and the Caribbean, while the region of Asia and Oceania saw its total increase by two to 17.

Regarding the type of exports, dependence was predominantly on agricultural products. This was the case for 41 percent of the countries, while 30 percent depended on fuel exports and 23 percent on minerals, ores and metals.

More than half of the countries depending on agricultural commodity exports, and two thirds of countries relying on minerals are African. The region of Asia and Oceania was home to almost half of those dependent on fuel exports.

UNCTAD defines a country as dependent on commodities when its commodity exports account for more than 60 percent of its total merchandise exports in value terms. When this share exceeds 80 percent, the country is considered “strongly commodity export dependent”, which was the case for seven out of 10 commodity-dependent developing countries in 2014 and 2015.