British respondents put the current Muslim population at 15%, three times the 2010 figure, while they overestimated the projected 2020 population by an even greater margin (22% versus an actual projection of 6%).
In the US the average estimate was Muslims accounted for one in six people, whereas Pew put the actual figure at one in 100, while the future projection was even further off the mark.
Australian respondents’ average estimate was that 12.5% of the country was Muslim, where the true figure is 2.4%. Their future projection of 21% was far off the actual projection of 3%.
The average French estimate was that 31% of the population was Muslim – almost one in three residents. France’s Muslim population actually stood at 7.5% in 2010, or one in 13 people. French respondents were also widest of the mark when it came to the projected Muslim population in 2020. The average prediction was that Muslims would make up 40% of the French population in four years’ time, almost five times the 8.3% Pew Research projection.
Italian, German and Belgian respondents all guessed that more than a fifth of the resident population was Muslim, while in reality the figure ranges from 3.7% in Italy to 7% in Belgium. All three countries also greatly overstated the expected proportion of Muslim residents in 2020.