Well... Maybe I have bit off more than I want to chew.

Short of me coding for each of your tables... Also, now knowing that you are using the various tables dependant upon one another, I would stick close with what you have now. The diesel table is similiar to the gasoline, so I could duplicate the same results as the example I posted earlier. As for checking for available updates on the other pages?

Natural gas
Petroleum
Monthly Energy Data (STEO Table Browser)

The above three provide in page information about the published date. If you think it will suffice us to simply check the last update (of your queries) against the publish date of these three pages to determine if your query should be refreshed, then that would be a breeze.

What do you think?

BTW. Which diesel do you import? "Average All Types" and/or "Low and Ultra-Low Sulfur"?