The Holderness Coast in East Yorkshire is one of Europe's fastest-eroding coastlines, characterized by weak boulder clay cliffs and high-energy marine processes.
Study the dataset below, which shows the cumulative cliff retreat (measured in metres from a baseline established in 2014) at a monitoring station near Great Cowden.
| Year | Cumulative Cliff Retreat (mmm) |
|---|---|
| 2014 | 0.0 |
| 2015 | 1.8 |
| 2016 | 4.2 |
| 2017 | 6.5 |
| 2018 | 8.1 |
| 2019 | 11.3 |
| 2020 | 14.0 |
| 2021 | 16.2 |
| 2022 | 19.5 |
| 2023 | 22.1 |
| 2024 | 24.5 |
Using the data in the table, calculate the mean annual rate of cliff retreat at Great Cowden between 2017 and 2023.
1.8 m/year1.8\text{ m/year}1.8 m/year
2.2 m/year2.2\text{ m/year}2.2 m/year
2.6 m/year2.6\text{ m/year}2.6 m/year
3.1 m/year3.1\text{ m/year}3.1 m/year
