There are 1,068,573 households in the municipality, giving an average household size of 3.3 people. Of those households, 78.4% are in formal structures (houses or apartment), while 20.5% are in informal structures (Shanty town). 94.0% of households use mains electricity for lighting. 87.3% of households have water supply to the dwelling, while 12.0% have piped water through a communal tap. 94.9% of households have regular refuse collection service. 91.4% of households have a flush toilet or chemical toilet, while 4.5% still use a bucket toilet. 82.1% of households have a refrigerator, 87.3% have a television and 70.1% have a radio. Only 34.0% have a landline telephone, but 91.3% have a cellphone. 37.9% have a computer, and 49.3% have access to the Internet (either through a computer or a cellphone).. What type of households are considered formal structures?