Figures in constant (2020) US$ are present according to calendar year, calculated on the assumption that, where financial years do not correspond to calendar years, spending is distributed evenly through the year
| Date | Valeur | Modifier , % |
|---|---|---|
| 2021 | 22 501 | 3,14 % |
| 2020 | 21 817 | 4,14 % |
| 2019 | 20 948 | 0,60 % |
| 2018 | 20 822 | 1,22 % |
| 2017 | 20 572 | 4,28 % |
| 2016 | 19 728 | 5,29 % |
| 2015 | 18 736 | 1,43 % |
| 2014 | 18 471 | 7,65 % |
| 2013 | 17 158 | 3,12 % |
| 2012 | 16 640 | 1,92 % |
| 2011 | 16 327 | 0,66 % |
| 2010 | 16 219 |