The left part of this page shows how should be the repartition of the 144 tiles in the beginning of the game. A hand of 13 tiles usually content :
Type | Mean number |
---|---|
Bamboos | 3,25 |
Dots | 3,25 |
Characters | 3,25 |
Winds | 1,4 |
Dragons | 1,1 |
Flowers | 0,7 |
It explains why hands with a lot of honors should be rare or difficult to achieve, and why it's usually easier to play with chows and families.