A question about a recipe: Aunt Mariah's Lemon Sponge Cups

I have a question about "Aunt Mariah's Lemon Sponge Cups" from ENunn.
How much of the mixture should I pour in each ramekin? I am relatively unfamiliar with making souffle style dishes and I'd like some guidance on this point - should I fill them half-way up? 3/4 of the way up? Thanks!