Drinking water supply and sanitation in Egypt is characterised by both achievements and challenges. Among the achievements are an increase of piped water supply between 1990 and 2010 from <answer>89% to 100%</answer> in urban areas and from 39% to 93% in rural areas despite rapid population growth, the elimination of open defecation in rural areas during the same period, and in general a relatively high level of investment in infrastructure. Access to an improved water source in Egypt is now practically universal with a rate of 99%. About one half of the population is connected to sanitary sewers.
From 1990 to 2010 what was improvement in piped water supply to urban areas?
89% to 100%