Anthropometry is the science that measures the range of body sizes in a population. When designing products it is important to remember that people come in many sizes and shapes.
Anthropometric data varies considerably between regional populations. For example, Scandinavian populations tend to be taller, while Asian and Italian populations tend to be shorter.

Percentile Humans
Anthropometric dimensions for each population are ranked by size and described as percentiles. It is common practice to design for the 5th percentile (5th%) female to the 95th percentile (95th%) male. The 5th% female value for a particular dimension (e.g. sitting height) usually represents the smallest measurement for design in a population.
Conversely, a 95th% male value may represent the largest dimension for which one is designing. The 5th% to 95th% range accommodates approximately 90% of the population.
To design for a larger portion of the population, one might use the range from the 1st% female to the 99th% male.