Summer Time

Globally, the use of summer time, as many countries call the change, shows a strong north-south divide.

The vast majority of countries using it are in the northern hemisphere, while the vast majority of countries south of the equator don't change their clocks during the longer periods of daylight in the austral spring and summer..

Source: http://www.csmonitor.com/USA/2010/0313/Daylight-Saving-Time-Remind-me-again-why-we-spring-forward