Честотата се определя като: много чести (≥1/ 10), чести (≥1/ 100 дo < 1/ 10) и нечести (≥1/ 1 000 дo < 1/ 100).
Frequency is defined as very common (≥ 1/ 10), common (≥ 1/ 100 to < 1/ 10) and uncommon (≥ 1/ 1,000 to < 1/ 100).