CREATE TABLE table_29778616_1 (intro_date VARCHAR2, throughput VARCHAR2)

What is the intro date for the throughput of 16 mbit/s?
SELECT intro_date FROM table_29778616_1 WHERE throughput = "16 Mbit/s"
SELECT "intro_date" FROM "table_29778616_1" WHERE "16 Mbit/s" = "throughput"