Madonna was the highest-grossing pop act of 2008, but the amount of album sales the singer sold, is at its lowest in 11 years reflecting the decline in CD sales.

Aaccording to Calendar's Ultimate Top 10, an annual survey that combines sales of concert tickets, albums and digital downloads to measure the years most popular acts, Madonna was the top overall pop act of the year.

Her Sticky & Sweet tour alone was the highest-grossing worldwide music tour this year, making a total of $281.6 million, according to Pollstar, the concert tracking magazine.

In terms of album sales, she sold $12.5 million in album sales in addition to download of $2.3 million.

In spite of leading, Madonna's album sales total is at the lowest for a No. 1 since the Ultimate Top 10 began in 1997, when the Rolling Stones posted $100 million on concert ticket and album sales.

The record belongs to 'N Sync, which earned $212.9 million in 2000 at the height of teen pop.