Populations of 695 representative terrestrial species are tracked to calculate the Terrestrial Living Planet Index. This index shows us the status of populations of terrestrial species in comparison to what it was in 1970.
If the total terrestrial species population in 1970 is taken as 100 units, then in 2003 only about 69 units were left. The terrestrial species index therefore shows a 31% decline from 1970 to 2003.

