Lower disposable income hampered consumer spending on books during the past five years. A transition toward digital technology also dented Global Book Publishing industry revenue due to the difficulty of pricing e-books, which are intrinsically different from printed products. The investments necessary to transition toward digital publishing also led to consolidation within the industry; they resulted in a 0.7% annualized decline in firms to 16,308 in the five years to 2013. New forms of entertainment also forced book publishers to increasingly compete with other media, including self-publishers and free e-books. Consequently, the industry is forecast to decline at an annualized five-year rate of 2.6% to total $108.4 billion in 2013, which includes a 2.0% drop in 2013 alone.