| Characteristic | 2015 | 2016 | 2017 | 2018 |
|---|---|---|---|---|
| - | - | - | - | - |
| - | - | - | - | - |
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Source
Release date
April 2019
Region
North America
Survey time period
2015 to 2018
Supplementary notes
Values prior to 2018 were taken from previous editions which can be accessed .
Values have been calculated by ÌÇÐÄÆÆ½â°æ using the total revenue and revenue percentages per service provided by the source.
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