You can go to Israel’s central burea of Statistics website they have the ratios broken down by district and religion. In ’07 they ranged from 102.2 to 106.7 per 100. I remember seeing something more specific but I do not remember where right now.
Regarding going off the derech I think we have to define the term. If it means completely leaving the orthidox community and that number is 6% and the ratio is skewed very heavily in the direction of boys then you are right we have an even bigger problem.
Since I have as of yet not been able to obtain any hard numbers on this I can only go by my own experience and that of people I have spoken to.
It should be noted that GOTD is only one reason people become unmarriageable. There are others, some of which pertain disproportionately to girls.
Re the math all I meant is that you don’t take the boys reduce them by six percent and then add four percent. You first add four percent then you reduce it by 6%. It does not make such a big defference when you are only talking about one year but if you keep going it makes a big difference.
Re the ratio of men to women – Women do not outnumber men until about age 60. You can look at the CDC’s website they have death rates broken down by gender.