This is a chart of the exchange rate between U.S. dollars and Russian rubles. The vertical axis is a measure of how many rubles are worth one dollar on a given day. You'll note that the rate has gone from just over 23 rubles per dollar to 32 rubles per dollar over the course of this graph. That means that the dollar is worth 40% more in rubles at the right end of the chart than it was at the left end of the chart. And how much time is represented by the horizontal axis? Six months.