Helllo99
I do believe that the growth rate is that high and likely even (4%-4.5%) higher based on work done by other people(using a stricter definition of yeshivish)I used the Avi Chai study bec it is readily available.
Re the 5% more boys born the relevant question is how many more marriageable boys than girls are there at the age 20. As boys have a higher mortality rate particularly in the teenage years, the ratio of boys to girls at age 20 is closer to 103:100 (according to the cdc if my memory serves me correctly – It has been a while since I looked it up). Presumably in the frum community that ratio is higher due to a lower rate if high risk activities. There is also the morbidity rate which is also higher among boys. The point is that 5% at birth is not 5% at marriage. Taking everything into account I would the number at about 8%.
I believe the 13% AZ mentioned was based on an actual tally of girls still single at the point where there are relatively few corresponding boys – you can ask him to be sure.
Regardless of the precise number and reason for it lowering the age gap will help.