90% of the National Debt was created by Reagan and the two Bushes.
Go to reaganbushdebt.org to see the numbers.
The debt is $18 trillion. According to your 90% claim, at least $16.2 trillion was created before Obama came into office (which would not account for debt created by every other president besides Reagan and the Bush duo).
Now, we can test your claim. In order to do this we shall compare the actual debt when Obama took office to the figure that results from calculating your claim.
Actual debt when Obama took office = $10.6 trillion
Calculated debt, per your claim = $16.2 trillion
$10.6 trillion < $16.2 trillion
Therefore, you are a lying sack of shit.