According to a more recent Pew Forum report which examined American religiosity in 2014 and compared it to 2007, there were 50.9 million adult Catholics as of 2014 (excluding children under 18), forming about 20.8% of the U.S. population, down from 54.3 million and 23.9% in 2007. Pew also found that the Catholic population is aging, forming a higher percentage of the elderly population than the young, and retention rates are also worse among the young. About 41% of those "young" raised Catholic have left the faith (as opposed to 32% overall), about half of these to the unaffiliated population and the rest to evangelical, other Protestant faith communities, and non-Christian faith. Conversions to Catholicism are rare, with 89% of current Catholics being raised in the religion; 8% of current Catholics are ex-Protestants, 2% were raised unaffiliated, and 1% in other religions (Orthodox Christian, Mormon or other nontrinitarian, Buddhist, Muslim, etc.), with Jews and Hindus least likely to become Catholic of all the religious groups surveyed. Overall, Catholicism has by far the worst net conversion balance of any major religious group, with a high conversion rate out of the faith and a low rate into it; by contrast, most other religions have in- and out-conversion rates that roughly balance, whether high or low. This is credited to the more liberal stance of the Church since Vatican II, where conversion to Catholicism is no longer encouraged, and the de-emphasizing of basic Catholic religious beliefs in Catholic education. Still, according to the 2015 Pew Research Center, "the Catholic share of the population has been relatively stable over the long term, according to a variety of other surveys  By race, 59% of Catholics are non-Hispanic white, 34% Hispanic, 3% black, 3% Asian, and 2% mixed or Native American. Conversely, 19% of non-Hispanic whites are Catholic in 2014 (down from 22% in 2007), whereas 48% of Hispanics are (versus 58% in 2007). In 2015, Hispanics are 38%, while blacks and Asians are still at 3% each. Because conversion away from Catholicism is presently occurring much more quickly among Hispanics than among non-Hispanic whites, it is unclear whether they will outnumber non-Hispanic whites among Catholics or not in the foreseeable future.
Question: How many more million adult Catholics were there in 2007 compared to 2014?
Answer: 3.4