Table:
text: List of world cups and world championships for juniors and youth
Men
Men
Sport Competition_name Competing_entities Age_groups Held_every
Rugby union Under 19 Rugby World Championship Nations 19 or younger Year
Rugby union Under 21 Rugby World Championship Nations 21 or younger Year
Speed skating World Junior Speed Skating Championships Individuals and Nations 19 or younger One year
Speed skating ISU Junior World Cup Speed Skating Individuals and Nations 19 or younger One year
Sailing ISAF Youth Sailing World Championships Nations Under 19`s annually
Sailing ISAF Classes World Championship Held in the Optimist, Splash, Zoom, RS Tera etc. 19 or younger Various
Table tennis World Junior Table Tennis Championships Individuals [D ] and Nations 18 or younger One year
Volleyball Men`s Junior Volleyball World Championship Nations 21 or younger Two years
Volleyball Boys Youth Volleyball World Championship Nations 19 or younger Two years

Question: How often does the men's table tennis competition take place at world cups and world championships for juniors and youth?