How long did Telemachus search for his father, Odysseus?

In Homer's The Odyssey, Odysseus is trying to make his way back to Ithaca after the Trojan War. While Odysseus faces obstacle after obstacle that keep him from going home, his wife Penelope and son Telemachus are harassed by suitors who want to marry Penelope. 
The goddess Athena tells Telemachus that he should go out into the world in search of information about Odysseus, and when he agrees, she provides him with a ship and crew. When Telemachus leaves Ithaca, Odysseus has already been away from home for 20 years. Telemachus only spends 1 year away from Ithaca on his search, but with the help of Athena, he and Odysseus end up returning to Ithaca at about the same time. While his journey may not have been as long as his father's, Telemachus's time away from Ithaca helps him to grow as a man.