Chadillac Nerd level : Epic ( sucess ! )
As for your population estimates, in french we say : Les années se suivent, mais ne se ressemblent pas ! ( Years follow each other, but are not alike )
So it's pretty hard to exactly tell especially with a boundary change.
But I'm like all of you. I'm so nerd, that I can't stand a year long without making my own population estimates !
I'm personally using another way to calculate a metro area.
Here's how I do it :
Per example , I take Québec city metro area ;
In 2011 (july 1st) the population of the province was 8 007 000
Québec city was : 776 800
So it counted for 9,7015 % of the province
I do it for 2012, 2013 etc... until today.
I think it's a good way to do it, because you can follow a tendency through the years. You can't be SO FAR of the reality when you reach 2014, because you will know that a metro area can't count ( with the same known boundaries ) for 9.7015% one year, and 10.123% another year when the difference is only 0.10 % since last year.
What do you think ?