<u>21.2 percent involved illicit drugs 14.3 percent involved alcohol, in combination with other drugs.
</u>
<h3>Explanation:</h3>
<u>(either alone or in combination with another drug)</u> increased 98.4 percent between 2004 and 2009, Patients aged 20 or younger accounted for 19.1 percent (877,802 visits) of all drug-related visits in 2009; about half of these visits involved drug abuse.