The given pie chart indicates some reasons for 
land
 degradation around the world Use synonyms
while
 the area was degraded by three continents Linking Words
during
 ten years from 1990 to 1999. Change preposition
over
Overall
, one hand, it can be seen that over-grazing and Linking Words
deforestation
 accounted for Use synonyms
two thirds
 of Add a hyphen
two-thirds
land
 degradation. Use synonyms
On the other hand
, in Linking Words
Northnorth
 America, Europe and Oceania, Correct your spelling
North North
over-cultivation
, Use synonyms
deforestation
 and Over-grazing were the most effective causes of Use synonyms
land
 disintegration  during a decade.
In the pie chart, 35% of Use synonyms
land
 depreciation belonged to over-grazing and it Use synonyms
followed
 by Add a missing verb
was followed
deforestation
 and Use synonyms
over-cultivation
 with less than a third and 28% respectively. Use synonyms
Moreover
, only other reasons with 7% caused to Linking Words
degrade
 Replace the word
degradation
the
 Change preposition
of the
land
.
In North America, Use synonyms
over-cultivation
 with 33% was the most effective cause Use synonyms
to degrade
 Change preposition
of degrading
land
; Use synonyms
however
, Linking Words
deforestation
 had the lowest proportion with almost nil (0.2%). In Europe, though Use synonyms
deforestation
 experienced the Use synonyms
the 
highest percentage of Remove the redundancy
apply
land
 decline with 9.8 % , over-grazing decreased by almost half (5.5 %). Use synonyms
Nevertheless
, in Oceania, over-grazing took place roughly ten times more than Linking Words
deforestation
. Use synonyms
In addition
, Linking Words
although
 Linking Words
over-cultivation
 never occurred in Oceania, North America and Europe saw it with 7.7% and 3.3%  respectively.Use synonyms