what is the rise of gas prices for the past 15 years?

Answer 1

Lets see, was about 20 cents a gallon in 69 then jumped 400% to over a dollar by 74 - then drifted between $1 and $2 for a long time with a slow permanent drift to almost $2. Then the next big spike seemed to happen after 911, went over $2 and swung between $2 and $3 until just recently.
Sorry, wish I had a chart for you.

Answer 2

That would be gas prices rising over the past 15 years. I dont think thats what you meant but its what you asked.