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 table_29778616_1 (intro_date VARCHAR, throughput VARCHAR)

### Question ###
What is the intro date for the throughput of 16 mbit/s?

### Accurate SQL ###

SELECT intro_date FROM table_29778616_1 WHERE throughput = "16 Mbit/s"