In what order were the runways built at Paris Charles de Gaulle?
Overview


(background image: Wikimedia)

Details

The first runway was finished in 1971 as 09/27 and it corresponds to todays 09R/27L:


  Work on the satellites started in late 1970. Also built were Air France and UTA hangars and a pooled cargo terminal.
  Construction on the first 11.800-foot (3,600-meter) runway, 09/28, and its associated taxiways started on August 1st, 1969.
  
  The runway was inaugurated by the Ministry of Transport on September 9th, 1971. The earthworks of Runway 2 were started in 1972.
  
  


(airporthistory.org)

The second runway was finished in 1976 as 10/28 and corresponds to todays 08L/26R:


  In 1976, Charles de Gaulle handled 7.5 million passengers and opened a second runway. Initially, the second runway was built at a reduced length of
  9.400 feet (2,900 meter) and without a parallel taxiway. It was only used as a backup when the main runway was inoperative or at the instruction of air
  traffic control. The runway could be built out to its full length of 11,800 feet (3,600 meters) and taxiways added when traffic demand required.


(airporthistory.org)

The following ground chart shows the layout in 1977:


(image source: flickr.com by jwhshd)

By 1994, the terminals had been greatly expanded to the south and the new runway was at its full length (I don't know when exactly the expansion happened):


(image source: flickr.com by jwhshd)

The third runway was finished in 1999:


  Expansion of Paris Charles de Gaulle (CDG) Airport has also helped Air France. A third runway at CDG opened in 1999, with a fourth to open in 2002.


(Strategic Management in Aviation: Critical Essays)

Unfortunately, the source does not detail which runway this was. By searching through pictures of CDG from 1999 on airliners.net, I was able to find the following quotes:


  Landing on runway 26L


(airliners.net, May 1999)


  Taxiing out runway 27


(airliners.net, May 1999)

This would suggest that the runway numbering had already changed and the second runway to the south (08R/26L) was built first (in 1999). This would leave runway 09L/27R to be the fourth runway added in the early 2000s.