The DHS conducted in 2007 pointed to coverage rates in Liberia that were significantly lower than official country reports. Despite an increasing trend between 2004 and 2009, WHO/UNICEF estimates illustrate a sharp decrease in coverage over the last two years. In 2011, Liberia’s immunization program failed to reach 39% (or 56,160) of its target population of children under one year of age with even a first dose of the DTP vaccine. Twelve percent of the children who began the DTP vaccination series did not complete it (drop out rate between DTP1 and DTP3), as shown in the graph below. Drop-out rates that are higher than 10% typically indicate problems with how immunization services are being delivered, perceived (e.g. friendly and reliable services) and used. The population’s use of routine immunization services is determined by the availability of, access to, demand for, and acceptance of those services.