(i) Percentage increase in the price of oil between 1998 and 2006.
In 1998 it was 12.7 and in 2006 it was 65.1
so equation is 12.7*x = 65.1 which is x=5.1259% or 5.13%(round figure).
Hence, (5.) 5.13% is the answer.
(ii) If the total oil supply had grown at the same rate as the former USSR oil supply between 2000 and 2006 how much would this have exceeded the demand in 2006?
rate of growth of former USSR oil supply between 2000 and 2006
In 2000 it was 7.9 and in 2006 it was 12.2
so the equation is 7.9*x = 12.2 which is 1.544%
According to question total oil suppy had grown @ the same rate i.e 1.544%
total oil supply in 2000 is 77.1
so the after growth 77.1 * 1.544 = 119.0424
Now, According to the question : how much would this have exceeded the demand in 2006?
Total Demand in 2006 is 84.7
Difference is 119.0424  84.7 = 34.3424
Hence (5.) 34.3 is the answer.
(iii) In which year was the largest combined change in supply from the previous year for OPEC, the former USSR and other NonOECD countries?
Supply
Supply 
OPEC 
USSR 
NonOCED 
Combined 
Difference 

1998 
31.0 
7.3 
15.7 
54 


1999 
29.6 
7.5 
16.0 
53.1 


2000 
31.0 
7.9 
16.2 
55.1 


2001 
30.5 
8.6 
16.4 
55.5 


2002 
28.9 
9.4 
16.9 
55.2 


2003 
30.6 
10.3 
17.1 
58 


2004 
33.1 
22.2 
17.7 
73 
Highest Value 

2005 
34.2 
11.6 
18.2 
64 


2006 
34.3 
12.2 
18.7 
65.2 


Hence, (4.) 2004 is the answer.