15Aggregate Demand Its ComponentsMedium1 mark
The table gives the national income of a country over six years.
| year | national income ($ billion) |
|---|---|
| 1 | 2200 |
| 2 | 2240 |
| 3 | 2260 |
| 4 | 2280 |
| 5 | 2310 |
| 6 | 2350 |
According to the accelerator principle, in which year did net investment first rise to a level above
that of the previous year?