Giovanni Amelino-Camelia, "Doubly-Special Relativity: First Results and Key Open Problems." Int. J. Mod. Phys. D11 (2002) 1643. Online copy at http://arxiv.org/abs/gr-qc/0210063
... 12.8% have a female householder with no husband present, and 24.0% are non-families. 19.0% of all households are made up of individuals and 7.0% have someone living alone ...