Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Name | Type | Year Built | Where Built | Length |
| --- | --- | --- | --- | --- |
| Messenger | sternwheeler | 1872.0 | Empire City | 91' |
| Juno | propeller | 1906.0 | Marshfield | 60.8' |
| Millicoma | sternwheeler | 1909.0 | Marshfield | 55' |
| Pedler | sternwheeler | 1908.0 | Marshfield | 124' |
| Fay No. 4 | sternwheeler (gasoline) | 1912.0 | North Bend | 136' |
| Life-Line | propeller (gasoline) | 1912.0 | Marshfield | 36' |
| Rainbow | sternwheeler | 1912.0 | Marshfield | 64' |
Question:
Where the length is 91', what is the year built?
Answer:
1872.0