The dominant phenotypes are not always more frequent than the recessive phenotypes
Let us examine a typical (thus rare) character of a single gene:
dominant allele + dominant allele = dominant phenotype
dominant allele + recessive allele = dominant phenotype
recessive allele + recessive allele = phenotype Recessive
Looking at this, you might conclude that the dominant phenotype is more common. But recessive alleles could be present in a high frequency in a certain population.
For example: in the color of the eyes, people with clear eyes tend to carry recessive alleles of key genes. Dark-eyed people tend to have dominant alleles.
In Scandinavia, most people have clear eyes, implying that recessive alleles of these genes are much more common in this region than dominant alleles.
