This map shows the Muslim population, and also ratio of each religions' population in the tooltip.
Pew Research Center estimated the population of each religious group in "The Global Religious Landscape"(2012). We can find that more than eight-in-ten people are affiliated to some religion and there are 23% of all population(1.6 billion people) are Muslims, which is the second largest number following Christians.
(Change in Population of Muslims)
Percentage of Muslim population in 1990 ................. 19.9% (1,050,963,000 people)
Percentage of Muslim population in 2000 ................. 21.6% (1,320,693,000 people)
Percentage of Muslim population in 2010 ............. 23.4% (1,619,314,000 people)
Projected Percentage population of Muslim in 2020 ..... 24.9% (1,913,499,000 people)
Projected Percentage population of Muslim in 2030 ..... 26.4% (2,190,154,000 people)
(Regional Distriburion of Muslims)
61.7% (985,530,000 people) of world Muslims live in Asia-Pasific
19.8% (317,070,000 people) of world Muslims live in Middle East-North Africa
15.5% (248,110,000 people) of world Muslims live in Sub-Saharan Africa
2.7% ( 43,490,000 people) of world Muslims live in Europe
0.2% ( 3,480,000 people) of world Muslims live in North America
0.1% ( 840,000 people) of world Muslims live in Latin America-Caribbean
73% of Muslims live in 49 countries in which they are religiously majority(97% of Hindus, 87% of Christians, 41% of Jews, and 28% of Buddhists as well).
The median age of Muslims(23 years) is relatively young. In all region above(Asia-Pacific, Middle East-North Africa, ...), regional median ages of Muslims are younger than overall regional median age.
Many of the data come from nation's census or so, and there will be unavoidable errors. For example, estimated Muslim population in China varies in rage of about 24 million(Pew Research) to "no less than 40 million"(PrayWay: http://www.prayway.com/unreached/main/china5.html) or even to 150 million(MuslimPopulation: http://www.muslimpopulation.com/).
*"0%", "100%" and "0 people" in the tooltip means "< 0%", "> 99%" and "< 10,000 people".
Data from The Pew Forum on Religion & Public Life,
"The Global Religious Landscape"(2012): http://www.pewforum.org/2012/12/18/global-religious-landscape-exec/
"The Future of the Global Muslim Population"(2011): http://www.pewforum.org/2011/01/27/the-future-of-the-global-muslim-population/
See Percentage and Size of Muslim Population by Country, ChartsBin.com, <http://chartsbin.com/view/24354> for visualized percentage of Muslim population.