The global NIR is the global "natural increase rate," which is simply the rate in which a population grows in a year. It is calculated by subtracting the crude death rate (total number of deaths per year for every 1000 people alive), and the crude birth rate (total number of live births per year for every 1000 people alive), and expressing the answer in terms of percentage (instead of the per 1000 basis).
The global NIR peaked in 1986, with a value of 2.2.
