A number of web sites given instructions on building population pyramids with Excel.Googling "population pyramids excel" will bring up a selection. A small number of the sites is listed below. Note that there is little difference in the process of creating pyramids for the different versions of Excel although pyramids developed in Excel for Apple need a bit of tweaking. The pyramids require data in five-year cohorts by sex. Suitable data at the national, regional and global levels can be downloaded from the World Bank's HNP database (only to 2010) at http://databank.worldbank.org/ddp/home.do , from the UN Population Division (1950 to 2050) at http://esa.un.org/unpd/wpp/index.htm/ using the "detailed data" selection. The US Census Bureau provides information (1995-2050) at http://www.census.gov/ipc/www/idb/informationGateway.php using Data Access option and the Age Groups tab.
Excel: For a step-by-step method for Excel, with perhaps more detailed instructions, go to http://www.best-excel-tutorial.com/56-charts/263-age-population-pyramid .
LibreOffice Calc: There appears to be no easily accessible instructions on the web for creating population pyramids in LibreOffice Calc. A set of instructions has been prepared but they require a basic knowledge of working with spreadsheets. For the instructions for LibreOffice Calc click here