The line graph shows the historical oil prices per barrel from 1973 to January 2009

The provided line graph illustrates the range of changes occurred in the cost of oil barrel from the year 1973 to January 2009. Data is collected by inflationdata. com and the Department of Revenue of Alaska. Overall, the prices of oil underwent various fluctuations reaching its peak around the final year but experienced sudden drop immediately by January 2009. Now turning to details, although the prices in the beginning was not high, it gradually gained its pace till 1979 (a little less than 40 dollars). But this value started showing some fluctuations for more than two decades since 1979. However, the cost gradually rose by three folds around 2006, which in turn showed a shard upward trend, reaching its peak with about 140USD. Inspite of this overwhelming raise, the selling price plunged after the year 2007. By January 2009, the value of the petroleum product was reduced by more than 3 times since it reached pick which is just above $40.