z-score calculation

hello.

Here are the data for 100 counties either receiving or not receiving funding for a given program. The data are % by year for a rate. I want to know if the increase from 2003 to 2007 is significant for the programs which received funding.

2003 2007

27 funded 26.59 37.58
73 not funded 18.49 26.62

How do I calculate a z score from these two proportions? In answering can you show your work for one such calculation using my data?

thanks.

paul