Nielsen SoundScan reports that sales of individually downloaded digital tracks are up more than 67% over the same period in 2005, accounting for more than 525 million digital downloads; This is 173 million more downloads than 2005’s annual total.

In 2006 to date, 54 tracks have sold more than 500,000 units as opposed to only 22 tracks in all of 2005. None reached that sales mark in 2004.

Digitally downloaded albums have increased more than 100% with 29.7 million YTD in 2006 versus 14.5 million in the same time period in 2005. In 2006 to date, 11 albums have sold more than 100,000 units digitally comparing to only 3 for the entire year in 2005 and none in 2004.

“It is clear that digitally downloaded music is continuing to enjoy tremendous and growing consumer acceptance,” said Rob Sisco, President Nielsen Music.

Nielsen’s numbers appear to contradict information released earlier in the week by Forrester suggesting that digital music sales are stagnating.

Historically digital downloads have dramatically increased year-over-year. In 2005, digital track sales reached 353 million; 150% higher than total track sales for all of 2004. In 2004, digital download track sales broke the 100 million mark with more than 140 million digital tracks sold.

Nielsen SoundScan tracks digital download sales from more than two dozen providers in the U.S. including every major digital music retailer. Nielsen SoundScan data coverage represents more than 95% of the digital music sales market.