user
Instruction
Answer the question based on the provided table.


Table
Table Title: Baltimore Americans
Table Content:
| Year | Division | League | Reg. Season | Playoffs | National Cup |
| --- | --- | --- | --- | --- | --- |
| 1934/35 | N/A | ASL | 6th | No playoff | ? |
| 1935/36 | N/A | ASL | 2nd | No playoff | ? |
| 1936/37 | N/A | ASL | 2nd, American | 1st Round | ? |
| 1937/38 | N/A | ASL | 4th, American | Did not qualify | ? |
| 1938/39 | N/A | ASL | 5th, American | Did not qualify | ? |
| 1939/40 | N/A | ASL | 2nd(t) | No playoff | Co-champion |
| 1940/41 | N/A | ASL | 3rd | No playoff | ? |
| 1941/42 | N/A | ASL | 5th | No playoff | ? |
| 1942/43 | N/A | ASL | 5th | No playoff | ? |
| 1943/44 | N/A | ASL | 3rd | No playoff | ? |
| 1944/45 | N/A | ASL | 4th | No playoff | ? |
| 1945/46 | N/A | ASL | 1st | Champion (no playoff) | ? |
| 1946/47 | N/A | ASL | 4th | No playoff | ? |
| 1947/48 | N/A | ASL | 4th | No playoff | ? |
| 1948/49 | N/A | ASL | Withdrew after 3 games | N/A | N/A |


Question
what year was the only year in which the team won the co-championship title?


Answer Format
The final answer should be concise and use the following format:
```json
{
    "answer": [
        "answer1",
        "answer2",
        ...
    ]
}
```
rule
["1939/40"]