Opioid sales increased more than eightfold between 1992 and 2015, according to a new analysis by the FDA that found no clear links between price and volume.

The bulk of the increase derived from oxycodone and fentanyl products, which comprised under $150 million in sales in 1992 but by 2009 accounted for $5 billion in sales and a market share of more than 70 percent.

Oxycodone, hydrocodone, fentanyl and morphine products accounted for less than 25 percent of opioids morphine milligram equivalents sold between 1992 and 1995, but reached an 80 percent share by 2011. By 2015, overall opioid sales had reached $8 billion.