What year was the team competition introduced in Tour de France?

Explanation

Since 1930, the teams have had their own, secondary competition in Tour de France. The ranking is based upon the three best riders from each team on each stage. These times are added, and the team that has used the least time, wins the team competition of the day. These times are then used for the overall ranking. The leading team in the competition today is wearing bright yellow/green numbers.