I remember calculating, partway into the series, that it was averaging about one month narrative time per novel. That must have compressed even more since then.

Around that time NR had said, in response to fan inquiries as to when Eve would have a baby, that it would not be until the end of the series if ever. Hah, I remember thinking that at that rate, Eve would be pregnant for 4 1/2 years reader time, which even the most eager baby-hoping fan would not enjoy.