In 2003, Montréal’s metropolitan area included a population of 3 574 500 inhabitants1 compared to an estimated population of 7 487 200 for the province of Québec2.
1 Statistics Canada. May 2, 2004. <http://www.statcan.ca/english/Pgdb/demo05a.htm>.
2 Statistics Canada. May 2, 2004. <http://www.statcan.ca/english/Pgdb/demo02a.htm>.
It is not a good idea to include numerous footnotes or endnotes at the end of a same sentence (separated by commas) because it would be difficult for the readers to know which statistic(s) and/or quote(s) – included in this particular sentence – the notes would refer to. To avoid any confusion, I definitely prefer the inclusion of a single note per sentence but this remains a personal choice. It is up to the author to decide!