This was 11.6 percent lower than the state average of 41.1 percent. In 2020 the total municipality population reached 205.
88.4 percent of the population had at least a high school diploma or the equivalent.
Degree distribution in Castana for 2020*
| Degree | Number of people | Percentage of population |
|---|---|---|
| No degree | 17 | 11.6 |
| Regular high school diploma | 38 | 26 |
| GED or alternative credential | 15 | 10.3 |
| Some college, less than 1 year | 23 | 15.8 |
| Some college, 1 or more years, no degree | 10 | 6.8 |
| Associate's degree | 28 | 19.2 |
| Bachelor's degree | 12 | 8.2 |
| Master's degree | 1 | 0.7 |
| Professional school degree | 0 | 0 |
| Doctorate degree | 2 | 1.4 |

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