The abover chart represents the inflation in Iceland throughout the last 12 months. The red fields symbolize price hikes. The green ones is when the price goes down.
What do the different sizes of the boxes mean? The inflation index is calculated using sort of an weighted average of different products. Thus, small increase in price of gas counts more than a similar increase in price of say, canned tomatoes. Thus, the greater the weight of the category/product, the larger box it gets in the chart.
The red field for Gas&Oil represents about 20% increase. If you are interested in the original data it can be found here:
The file used for producing this graph can be found here: inflation2011.