According the API guide you can use the options condition in a URL to define how many results to show:
You use the options parameter to further control the return of records. You can use any or all of the options, separating the options with a period.
num-n
--specifies a maximum of n records in the return
&options=num-15
However, it doesn't work. There are a lot of things in the API guide that don't work.
So you are stuck to with the forces that are for now.
Unless you want to do some custom code to manipulate the current system.