2. 20 points * (percentage of correct units for hardware system); anything over 100% difference = 0 points. Maximum points: 100.
Notes:
For 2007-2009, PS2 was included, so the maximum was 120 points.
For 2011, January/February were 25 points per system with PSP dropped. With 3DS's release in March, it shifted back to 20 points per system.
For 2012, January was 25 points per system with NDS dropped. With PSV's release in February, it shifted back to 20 points per system. When Wii U releases, it'll shift to 16.667 points per system to keep all months having 100 points per system per month.
3. Bonus points for finishing in the top 10 by units for the month:
#1 - 17 points
#2 - 13 points
#3 - 11 points
#4 - 9 points
#5 - 7 points
#6 - 5 points
#7 - 4 points
#8 - 3 points
#9 - 2 points
#10 - 1 point