It's called a linear regression. And your data results in a 'not too accurate' one.
A quartic regression would be better.
Using your data I get a quartic of
This has an R^2 of 1 and that is as good as it gets.
When doing a regression, the closer R^2 is to 1, the better.
A linear regression resulted in about .4. That is bad.
You can do these with Excel or any decent calculator.