A much more informative graph would map relative growth versus countries that didn't "join the club" (say, Norway, Switzerland or others).
I'm not British, and I'm not sure whether I'd vote for or against if I were, but it's interesting.
There is a positive vision for brexit, which about being open to the world, embracing free trade, free movement of labour, and reducing regulation.
The current version immigration system is broken. Any one with little skills can come to the UK from Europe. A doctor from outside Europe will have real difficultly. Personally I want both people.
Leaving the EU wouldn't effect our border controls, because they aren't set by the EU.
The UK isn't part of the "Schengen Area" of countries without mutual border control. The UK has control over its border policy, despite what brexit campaigners claim. It is the UK government that chooses to implement border policies which are regarded by some as "too lax", and then, sometimes, chooses to blame the EU for it.
You appear to be confusing border control and EU immigration. We control the former and not the latter.
I am voting leave but not for the reasons that are spotlighted by the mainstream media. I know that in the short-term there is some risk however I believe it is surmountable. I am much more worried by what will happen to this country if we remain in the EU over the next decade.
[0] http://www.adamsmith.org/the-liberal-case-for-leave
[1] http://www.adamsmith.org/evolution-not-revolution