In a conservation reserve, a population of a rare wild orchid species is monitored over time. The orchids grow in two distinct sub-habitats: dry grassland and wet meadow.
The table below shows data on this orchid population in July 2015 and July 2023.
| Date | Total number of orchids / thousands | Percentage in dry grassland (%) | Percentage in wet meadow (%) |
|---|---|---|---|
| July 2015 | 18.40 | 28 | 72 |
| July 2023 | 22.15 | 36 | 64 |
Use the table to calculate the increase in the number of orchids in the dry grassland sub-habitat between July 2015 and July 2023.
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