It would be very surprising if the rate was steady. Boomers are ages 59 to 77 today. The ones who have died have been on the younger side, but it won't be long until most are within a standard deviation for average lifespan.

Also, there weren't the same number of boomers born every year. In fact, 1946 had a spike of them, and the rate started falling off each of the last seven years or so of the range. So we started with more older boomers than younger boomers.