A census performed in 1998 estimated that 1.3 million breeding pairs occurred worldwide.
But others have formed choirs in other cities, and, Mr. Kochta-Kalleinen said, more than 60 performances have occurred worldwide — from Melbourne to Singapore to Philadelphia to Florence.
Rubella occurred worldwide before immunization programs were instituted, with minor epidemics arising every 6 to 9 years and major epidemics every 30 years.
Fifty-two shattacksacks have occurred worldwide this year, including three fatal ones, said George Burgess of the International Shark Attack File in Gainesville, Fla. Twenty-nine of the attacks have been in Florida waters.
Further warming might result in the replacement of deciduous forest by grassland, as has occurred worldwide at the steppe- or prairie-forest border in response to climatic changes over recent centuries.
Several incidences of voltage instability have occurred worldwide recently.
In less than one decade, several large subduction earthquakes occurred worldwide.
Harmful algal blooms (HABs) have increasingly occurred worldwide and pose serious threats to water environment safety.
EHNC estimates that 200 million to 500 million online payment card transactions occurred worldwide in 1999.
These cases are among the most common reservoir models occurred worldwide especially in the Iranian oil reservoirs.
An estimated 804,000 suicides occurred worldwide in 2012, representing an annual global age-standardized suicide rate of 11.4 per 100,000 population (15.0 for males and 8.0 for females).
