The 2011 season has seen the introduction of a number of major rule changes, most notably the implementation of the Drag Reduction System (DRS) and the the return of Pirelli. With TV viewing figures on the rise, the changes appear to be a popular success. But what has been the effect of the new regulations so far? As we approach the halfway point of the season, here are the numbers to make an assessment...

How many overtaking manoeuvres have been made in the first nine races?
The raw total of overtaking manoeuvres during the first nine races is 623, including moves between team-mates, and passes by faster cars on the bottom three teams. This doesn't include overtakes on the first lap or passes made because of damage.

What is the breakdown of overtaking manoeuvres?
Of the 623 passes, 175 were by faster cars on the bottom three teams and 43 were between team-mates. There have been 180 DRS-assisted passing moves, and 225 'normal' (i.e. non-DRS) passes.

Which races have seen the most passing?
The top three races, using raw totals, were Montreal (136 passes), Istanbul (123 passes) and Shanghai (97 passes). The fewest were Monaco (22 passes), Silverstone (29 passes) and Melbourne (30 passes). Interestingly, the race in Valencia featured 44 passes - twice as many as in Monaco. Of these, 16 occurred in the first DRS zone and six in the second.

What has been the influence of DRS on overtaking?
DRS has accounted for 29% of passing manoeuvres in 2011. DRS passes have outnumbered normal passes at four races: Shanghai (33% of total), Istanbul (41% of total), Barcelona (35%) and Valencia (50%). The highest number of DRS passes was at Istanbul (50), followed by Shanghai (31) and Barcelona (29). The fewest were in Monaco (2), Melbourne (5) and Silverstone (6).

What has been the balance between DRS passes and normal passes?
The race in which DRS passes outweighed normal passes to the greatest extent was Valencia: 50% of passes were DRS-enabled, compared to 11% of normal moves. The race at which normal passes outweighed DRS moves to the greatest extent was Monaco, with 64% of normal moves compared to 9% of DRS moves. The next most extreme was Silverstone, with 55% of normal moves compared to 21% of DRS-assisted passes.

How much passing has been done on the first lap?
Although it could be argued that the new rules have diminished the importance of track position in the early stages of the race, a good first lap remains an important asset. Nico Rosberg and Michael Schumacher have only lost position on the first lap on three occasions between them this season (excluding the damage Schumacher sustained on lap one in Melbourne). He has made up three or more places on the first lap on four occasions; the best was a gain of five places on lap one in Shanghai.