A new study says low-income Americans are facing a higher unemployment rate today than at the height of the Depression. The Center for Labor Market Studies at Boston’s Northeastern University divided US households into ten groups based on annual income. The lowest tenth, with an annual household income of $12,499 or less, had a fourth-quarter unemployment rate last year of 30.8 percent. The next lowest-income group had an unemployment rate of 19.1 percent. The top two groups, with incomes above $100,000, had an average unemployment of 3.6 percent.