9. The accompanying table shows data on the total number of people in the United States and the number of all people who were uninsured, for selected years from 1999 to 2011. It also shows data on the total number of poor children in the United States—those under 18 and below the poverty threshold—and the number of poor children who were uninsured.
For each year, calculate the percentage of all people who were uninsured and the percentage of poor children who were uninsured. How have these percentages changed over time? What is a possible explanation for the change in the percentage of uninsured poor children?
| Year | Total people | Uninsured people | Total poor children | Uninsured poor children |
| (millions) | ||||
| 1999 | 276.8 | 38.8 | 12.3 | 3.8 |
| 2001 | 282.1 | 39.8 | 11.7 | 3.3 |
| 2003 | 288.3 | 43.4 | 12.9 | 3.3 |
| 2005 | 293.8 | 44.8 | 12.9 | 3.1 |
| 2007 | 299.1 | 45.7 | 13.3 | 3.1 |
| 2009 | 304.3 | 50.7 | 15.5 | 3.1 |
| 2011 | 308.8 | 48.6 | 16.1 | 3.0 |
Data from: U.S. Census Bureau.