How often do volcanoes around the world erupt?

Question

I'm trying to do a comparison between human pollution and natural pollution (i.e. from volcano eruptions). I am looking for an annual average on how many volcano eruptions occur in the world. Any ideas would be greatly appreciated. I realize they are not on a schedule, I am merely looking for an average or set number over the last century

Answer 1

There are about 15 continually active volcanoes worldwide. The rest have erupted periodically during the last 10,000 years and remain potential hot spots. The average number of eruptions yearly remains curiously constant -- 50 to 60.

http://findarticles.com/p/articles/mi_m1...

About 50-60 volcanoes erupt every year. About half are effusive (lava flows) and half are explosive.

http://www.geocities.com/dtmcbride/hist/...

Answer 2

they are not on a schedual!