Please review my IELTS writing task 1

Topic : Cambridge IELTS 8 test 1

My essay:

Given are two figures showing four different reasons cause worldwide land degradation ( over-grazing, deforestation, over-cultivation, and other ) and how their impact on three regions in the world ( North America, Europe, and Oceania) in 1990s.

Overall, of these regions, Europe was responsible for the largest proportion of land which became less productive while the least percentage was in North America.

The main cause of global land degradation was over-grazing, which accounted for 35% of land degraded. It was followed by deforestation and over-cultivation, stood at 30% and 28% respectively. A mere of 7% of degradation was caused by other reasons.

In Europe, deforestation accounted for the largest proportion of land degraded (9,8%), while its effect on Oceania and North America was insignificant, at merely 1.7% and 0.2%. Europe, which had the largest percentage of total land degraded(23%) also suffered from over-cultivation and over-grazing, which caused 7.7% and 5.5% of land degradation respectively. It was followed by Oceania with a total of 13% of land degraded, which was mainly due to over-grazing (11.3%). North America had least proportion of land degraded, at a mere 5% during 1990s, and the main causes of this were over-cultivation(5%) and to a lesser extent, over-grazing(1.5%)