You're correct. Their voting system uses proportional representation, in which each party receives a number of seats proportional to the percentage of votes they received.
Edit: http://en.wikipedia.org/wiki/Politics_of_the_Netherlands#Pol...
Edit: http://en.wikipedia.org/wiki/Politics_of_the_Netherlands#Pol...
That is different from, for example, Germany, where seats are proportionally distributed among parties that got at least 5% of the votes.
So, the theoretical maximum number of parties in parliament is 150 in the Nethelands, but 20 in Germany.