According to this:
Irish birth and marriage rates rising - irishhealth.com, 20,000 marriages were registered in Ireland in 2003, which was the highest figure in 20 years. (Newer figures would be helpful here, but this was all I could find atm).
20,000 marriages for 12 months (or 15,000 for nine months) compares to 536 civil partnerships for nine months.
Our best guess at the moment is that gay people make up somewhere between 2% and 6% of the population.
2% of 15536 is 310, and 6% is 932,
So, if gay couples are entering into civil partnerships roughly in proportion to their representation as part of the total population entering into marriages and civil partnerships (going by the 2003 figures), we would expect to see the figure for nine months being somewhere between 300 and 900 (and it is: 536).
If I can find more up to date figures, I'll adjust the results accordingly.