Complex sentence: Through 2011 the Democratic Republic of the Congo had the lowest Human Development Index of the 187 ranked countries, classified lower than Niger despite a higher margin of improvement than the latter country from 2010's numbers.
Split into simpler sentences: Through 2011 the Democratic Republic of the Congo had the lowest Human Development Index of the 187 ranked countries. It ranked lower than Niger, despite a higher margin of improvement than the latter country over 2010's numbers.