Conversation so far:
What was Cibona?
Petrovic followed his brother's footsteps and moved to Cibona to form, at that time, the best backcourt duo in Europe.
What position did Petrovic play?
the best backcourt duo in Europe.
Did the team do well?
The very first year in Cibona he won both the Yugoslav League championship and the Yugoslav National Cup.
How many points per game did he score that year?
Petrovic's scoring average during the four years with Cibona stood at 37.7 points in the Yugoslavian first division and 33.8 in all of the European wide competitions.
Which season was his personal best?
CANNOTANSWER.
Did they win any more championships?
The same year brought another Yugoslav national cup title for Cibona.

Question: How many championships did he win with Cibona?
Self-contained rewrite: How many championships did Petrovic win with Cibona?