It is because the difference between consumption and produce of Edible oils is increasing yearly as illustrated in the diagram below.

SUPPLY OF EDIBLE OILS FOR THE the years 1996-97 to 2000-01 (In Lakh MT)
Year

Net availability of Edible Oils
from all domestic sources

Actual Consumption/Demand*

Import @

1996-97 70.89 83.72 11.29
1997-98 60.32 87.69 23.78
1998-99 69.61 91.99 41.96
1999-00 61.07 96.43 39.75
2000-01

54.54(T)

100.96*

46.92

Source : Ministry of Agriculture