Each year, the campers at Meg's summer camp try to set that summer's record for finishing the obstacle course as quickly as possible. According to the table, what was the rate of change between 2019 and 2020?
Year | Record time (minutes)
2016 | 21
2017 | 21
2018 | 22
2019 | 23
2020 | 28
Plug the numbers into the formula for rate of change and simplify.
Rate of change
 = \frac{change in value}{change in time}
 = \frac{28 minutes - 23 minutes}{2020 - 2019}
 = \frac{28 minutes - 23 minutes}{1 year}
 = \frac{5 minutes}{1 year}
 = 5 minutes per year
The rate of change between 2019 and 2020 was 5 minutes per year.