A table of the US minimum wage for 6 different years is shown below.
| Year | US minimum wage (dollars per hour) |
|---|---|
| 1960 | 1.00 |
| 1970 | 1.60 |
| 1980 | 3.10 |
| 2000 | 5.15 |
| 2010 | 7.25 |
What was the average annual increase in the US minimum wage, in dollars per hour, from 1960 to 2010? (Grid-in response)
