I had the same thought: .88% of today's Portugal GDP is only 2 billion USD.
But in retrospect, it looks like the comparison is being done to the US economy, given the readership. 150 billion USD is approximately .8% of US GDP. Should have been better explained, I agree.
I can accept 150 billion without any suspicion. Portugal just needed to have 75 times greater influence/more value back then in the known economy, than today. Sounds about right.
No it wouldn't. Probably an off by factor of 1000 error.