World democracies feature diverse legislative and executive institutions. These differences create varied power distribution systems post-elections.

This paper explores how institutional frameworks shape voter turnout patterns across elections in different countries.

The key finding reveals a novel contest effect: Under intermediate power sharing conditions, voter participation tends to follow an optimal curve - increasing then decreasing as the system becomes more proportional.

Furthermore, we demonstrate that overall turnover rates significantly improve when political systems maintain moderately balanced representation between parties. This result holds across multiple modeling approaches including rational choice frameworks and ethical voter models.

This study provides crucial insights for understanding how electoral institutions influence democratic engagement worldwide.