Between 1985 and 2003, more deaths due to tornadoes occurred in mobile homes than in any other type of structure or place. During this time, 40% of all tornado-related deaths occurred in mobile homes.
According to Census 2000, mobile homes made up only 7% of all occupied housing units in the US and the proportion of people who live in mobile homes was also around 7%. Since most tornadoes occur in tornado alley, I looked for statistics on mobile homes in the states in tornado alley. While a bit larger, the numbers do not differ that much from the nation. For example, roughly 10% of Oklahoma's housing units are mobile homes and roughly 8% of Texas' housing units are mobile homes. Kansas' proportion is less than 7%.
But in 2000, 68.3% of all deaths attributed to tornadoes occurred in mobile homes.
The lesson that many already know but that these data underscore: mobile homes are dangerous places to be in storms.