In the United States, about 7 percent of the male population—or about 10.5 million men—and 0.4 percent of the female population either cannot distinguish red from green, or see red and green differently from how others do (Howard Hughes Medical Institute, 2006).
U Sjedinjenim Američkim Državama oko 7% muške populacije – od prilike 10.5 milijuna muškaraca – i oko 0.4% ženske populacije nije u stanju razlikovati crvenu boju od zelene boje ili nije u mogućnosti vidjeti razliku između tih dvaju boja (Howard Hughes Medical Institute, 2006.).