| Year | All sectors | Public sector | Private sector |
|---|---|---|---|
| 2013 | 25.6 | 56.4 | 14.4 |
| 2015 | 24.7 | 54.8 | 13.9 |
| 2017 | 23.5 | 52.2 | 13.5 |
| 2019 | 22.8 | 51.7 | 13.2 |
| 2021 | 21.9 | 50.4 | 12.0 |
| Year | Public sector (%) | Private sector (%) |
|---|---|---|
| 2013 | 1.1 | 2.3 |
| 2015 | 1.3 | 2.5 |
| 2017 | 1.5 | 2.8 |
| 2019 | 2.0 | 3.1 |
| 2021 | 2.4 | 3.5 |
Using the data in Extract D (Table 2), calculate the difference between the mean percentage trade union density in the public sector and the mean percentage trade union density in the private sector over the period 2013–2021.
Give your answer to one decimal place.