The natural gas consumption in 2009 = $$\dfrac{8}{100}\left(1000\right)\ =\ 80$$

The natural gas consumption in 2010 = 5% increase from 2009 = 80(1.05)

Import of natural gas for the year 2010 = 50% of 80(1.05) = 42

The natural gas consumption in 2012 = 80(1.05)(1.1)(1.05)

Import of natural gas for 2012 = 30% of 80(1.05)(1.1)(1.05) = 29 (approx)

Hence the required difference = 42 - 29 = 13

So, from 2010 to 2012, the imports were reduced by 13 MTOE.