It's a recurring nightmare many people just don't want to think about. It's almost impossible to establish average gas prices these days, with the cost of gasoline rising so sharply so quickly. Seems every day brings news stories of record-breaking prices once again, with the threat of more tomorrow.

And the only thing that seems even more scary than thinking about average gas prices is looking at a chart of average gas prices over the last couple of years. Every point is up, up, up with nary a valley in sight.

It's impossible to consider average gas prices paid by the consumer without considering the average gas prices paid for crude and wholesale gasoline, too. After all, wholesale price is based on crude and retail is based on wholesale.

The prices per gallon below are taken from the American Automobile Association (AAA) during the last year and they represent regular unleaded gasoline only.

The average price per gallon of crude was:

• $1.51 on May 1, 2007
• about $1.75 on August 1, 2007
• about $2.15 on November 1, 2007
• about $2.50 on February 2008
• about $2.91 on April 29, 2008

Average gas prices for wholesale gasoline during that same time period are:

• $2.51 on May 1, 2007
• about $2.30 on August 1, 2007
• about $2.40 on November 1, 2007
• about $2.50 on February 2008
• about $3.00 on April 29, 2008

Here are the national average gas prices American consumers paid during that time:

• $3.05 on May 1, 2007
• about $2.80 on August 1, 2007
• about $3.01 on November 1, 2007
• about $3.00 on February 2008
• about $3.50 on April 29, 2008

Of course, not everybody drives a vehicle that uses regular unleaded gasoline. Here are some average gas prices for different grades of gasoline for today (April 29), for one month ago, and for one year ago:

• Regular gasoline today: $3.607
• Regular gasoline one month ago: $3.286
• Regular gasoline one year ago: $2.953

• Mid-grade gasoline today: $3.830
• Mid-grade gasoline one month ago: $3.489
• Mid-grade gasoline one year ago: $3.134

• Premium gasoline today: $3.968
• Premium gasoline one month ago: $3.616
• Premium gasoline one year ago: $3.248

• Diesel today: $4.244
• Diesel one month ago: $4.023
• Diesel one year ago: $2.922

Average distance to be traveled during this year's summer vacation road trip? Probably less than last year's.