| Characteristic | 2014 | 2015 | 2016* | 2017** | 2018** |
|---|---|---|---|---|---|
| - | - | - | - | - | - |
| - | - | - | - | - | - |
| - | - | - | - | - | - |
| - | - | - | - | - | - |
| - | - | - | - | - | - |
| - | - | - | - | - | - |
| - | - | - | - | - | - |
| - | - | - | - | - | - |
| - | - | - | - | - | - |
| - | - | - | - | - | - |
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Region
Worldwide
Survey time period
2014 and 2015
Supplementary notes
*Estimate.
**Forecast
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