I wondered how internet usage featured in this, so I referred to
<a href="http://www.bls.gov/tus/" rel="nofollow">http://www.bls.gov/tus/</a>
In there it says "Computer or Internet use may be coded as work, education, volunteering, or relaxing, depending on how the respondent identified the activity during data collection".
So the answer is that it is spread all through depending on what the user was using the internet for at the time. This includes shopping.