The following graphs are for inbound and outbound traffic at the ports of Los Angeles and Long Beach in TEUs (TEUs: 20-foot equivalent units or 20-foot-long cargo container).
To remove the strong seasonal component for inbound traffic, the first graph shows the rolling 12 month average.
On a rolling 12 month basis, inbound traffic was up 1.6% compared to the rolling 12 months ending in February. Outbound traffic was up 0.8% compared to 12 months ending in February.
The downturn in exports in 2015 was probably due to the slowdown in China and the stronger dollar. Now exports are picking up again,
The 2nd graph is the monthly data (with a strong seasonal pattern for imports).
The Chinese New Year was early this year, so imports declined in February and rebounded in March
In general both exports and imports have been increasing.