The Port of Long Beach, whose problems instigated the post the OP is responding to, publishes container movements here:
They're up ~150,000 TEUs since early last year (just plotting the "total" column and eyeballing it). IIRC, most containers are 40', so that's somewhere around 75,000 more containers per month. Note that this it both inbound and outbound, full and empty.
There's enough uncertainty in both of those figures I wouldn't take it to the bank, but it shows that shipping volumes have increased at the port.