Just multiply Taylor's album sales for each album by the adjustment factor given in the table and you'll have the adjusted total to 1999's market.
Taylor Swift (2006) - 6,000,000 x 1.558 = 9,348,000
Fearless (2008) - 10,000,000 x 2.020 = 20,200,000
Speak Now (2010) - 6,000,000 x 2.644 = 15,864,000
Red (2012) - 6,500,000 x 2.782 = 18,083,000
1989 (2014) - 7,700,000 x (let's just 3.250 based on trends since there's no adjustment factor for 2015) = 25,025,000
Total: 88,520,000
