The source for the graph is listed right below it - any questions about the methodology can probably be answered by referring to the source.
Looks like we headed down to me.
Yes. The slight downward trend you notice is a result of the fact that the economy has been in recession since early 2001 or so. This recession also explains the number of businesses you see closing up shop and the number of auctions and what have you - the anecdotal evidence. Essentially, the effects you see are a result of the slowdown in the economy, not a result of trade policies.