Is a matter of presentation

This is the electric tariff for Singapore over the past years from 2006Q4 to 2011Q3.  On the primary Y-axis is the per barrel Fuel Oil Price (FOP) in Singapore $ and on the secondary Y-axis is the Low Tension Tariff (LTT - residence house hold) rate (cent/kwh).  The pink color line is the FOP while the blue line is the LTT.

What can you tell from the chart?

1. The variation in the FOP is huge
2. The variation in the LTT is small
3. The variation in the LTT vs the FOP is small or insignificant.

Now, if the secondary Y-axis has it max value change from 120 to 35.  Let see the effect of it.

The obervations.

1. Both FOP and LTT has huge variations
2. LTT variation become significant comparing to FOP variation.

Conclusion:
The way presentation material is done, it matter how the perception can be.  The FACT stays.