Thinking about making a book app? According to a new report from the Online Publisher’s Association, the paid app business doubled in the last year and growth is expected.

According to the report, tablet users spent an estimated $2.6 billion in 2012, up from $1.4 billon in 2011. The report also found that paid apps account for 23% of all apps downloaded in the past year, and that 72% of tablet users have paid for tablet apps in the past year.

AppNewser has more: “‘The OPA study reinforces the monetization opportunities on the device. Nearly a quarter of apps downloaded in the past year were paid,’ said Pam Horan, president of the Online Publishers Association. ‘It is very encouraging to see that consumers are opening up their wallets to access original content with the top paid content categories being magazines, entertainment, sports and weather.’”