| a | Break in series with previous year for which data is available |
| b | Secretariat estimate or projection based on national sources |
| c | National estimate or projection |
| d | Defence excluded (all or mostly) |
| e | National results adjusted by the Secretariat to meet OECD norms |
| g | Excluding R&D in the social sciences and humanities |
| j | Excludes most or all capital expenditure |
| l | Overestimated or based on overestimated data |
| m | Underestimated or based on underestimated data |
| o | Includes other classes |
| p | Provisional |
| t | Do not correspond exactly to OECD norms |
| w | Including extramural R&D expenditure |
| x | Confidential |