The access-to-electricity data are released through the Sustainable Energy for All (SE4ALL) database and collected among different sources: demographic and health surveys (DHSs) and living standards measurement surveys (LSMSs), multi-indicator cluster surveys (MICSs), the World Health Survey (WHS), other nationally developed and implemented surveys, and various government agencies (e.g., ministries of energy and utilities). Given the low frequency and the regional distribution of some surveys, a number of countries have gaps in available data. To develop the historical evolution and starting point of electrification rates, a simple modeling approach was adopted to fill in the missing data points: around 1990, around 2000, and around 2010. Therefore, a country can have a continuum of 0 to 3 data points. There are 42 countries with 0 data points, and the weighted regional average was used as an estimate for electrification in each of the data periods. 170 countries have between 1 and 3 data points, and missing data are estimated by using a model with region, country, and time variables. The model keeps the original observation if data are available for any of the time periods. This modeling approach allowed the estimation of electrification rates for 212 countries over these 3 time periods (indicated as "Estimate"). The notation "Assumption" refers to the assumption of universal access in countries classified as developed by the United Nations. Resource Watch shows only a subset of the data set. For access to the full data set and additional information, see the Learn More link.