Given the information on the table, we can see the following increases on the minimum wage:
From 1980 to 1981 : 0.25
1981 to 1990: 0.45
1990 to 1996: 0.95
1996 to 1997: 0.4
1997 to 2007: 0.7
2007 to 2009:1.4
As we can see, the minimum wage has a tendency to grow with the passing of the years, but there is not a constant of growth. Therefore, we could use the mean of these increments, and use it to estimate the approximate minimum wage for 2020. First we get the mean of this 6 numbers:
We have that, in average, the minimum wage increased 0.691 from 1981 to 2009, then, an approximation for the current year would be the following:
then, the minimum wage for the current year should be $14.84, because the mean of the increments of the given data would give us an approximate of $14.84