3DS hardware sales don't add up

[benji232]

If we look at the yearly sales charts on vgchartz for 3ds going from 2011 to 2014, we have:

2011: 13,250,062 units sold

2012: 14,112,182 units sold

2013: 14,420,949 units sold

2014: 2,636,122 units sold

Add that all up and you get: 44,419,315 units sold.

Yet, vgchartz has the total at 43.2m??