Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE ship ( built_year VARCHAR )

### Question ###
In which year were most of ships built?

### Accurate SQL ###

SELECT built_year FROM ship GROUP BY built_year ORDER BY COUNT(*) DESC LIMIT 1