The 2001 CIA World Factbook

by United States. Central Intelligence Agency

Sri Lanka:
18 years of age; universal

Sudan:
17 years of age; universal, but noncompulsory

Suriname:
18 years of age; universal

Swaziland:
18 years of age

Sweden:
18 years of age; universal

Switzerland:
18 years of age; universal

Syria:
18 years of age; universal

Tajikistan:
18 years of age; universal

Tanzania:
18 years of age; universal

Thailand:
18 years of age; universal and compulsory