Complex sentence: Phosphate is the chief product that accounted for 14% of the world's production in 2011, though the country holds 75% of the phosphate reserves of the world and is ranked third in its production and is its highest exporter.
Split into simpler sentences: Phosphate is the chief product and it accounted for 14% of the world's production in 2011. The country holds 75% of the phosphate reserves of the world and is ranked third in the world in its production and is its highest exporter.