World Space Week
International Literacy Day
International Day of Democracy
International Day For the Preservation of the Ozone Layer
International Day of Peace
World Maritime Day
64th Session of the United Nations General Assembly
International Day of Older Persons
International Day of Non-Violence
World Habitat Day
World Teachers Day
World Post Day
World Mental Health Day
World Population Day is marked by the United Nations every year on 11 July, as on this date in 1987, the world’s population was estimated to have reached 5 billion.
http://www.un.org/depts/dhl/population