The king called the first congress in 1906, and delegates attended from 40 countries.
About 250 delegates, said to include many young people, attended.
On April 24-26, 1912, the state held a meeting where 175 delegates from several areas attended.
It was attended by 44 delegates from 16 different countries.
In recent years, the conference has been attended by between 1,500 and 2,000 delegates.
It was attended by about 200 delegates from the council.
Elections for the congress were held in 48 countries and 529 delegates attended.
Each year, 5000 delegates from 50 nations attended the conference.
A further 102 delegates attended with speaking rights, but no vote.
Only 19 delegates attended the second convention, and 26 at the third.