What is wrong with this arrangement?: US Pays 22.14 % of NATO Budget; Germany 14.65 %; 13 Allies Pay Below 1%

President Trump has strongly suggested that many members of NATO are not paying their fair share. 
I think he's got a very good point. 

CNS News reports while President Trump’s weekend Twitter assertion that “Germany owes vast sums of money to NATO” is disputed by experts – and by Berlin – it draws attention to the fact that Germany, like the majority of the 28 members of the alliance, has yet to meet a NATO-agreed commitment to devote two percent of GDP to defense spending.

At the same time, a closer look at NATO funding also underlines that – as is the case with the United Nations – the U.S. contributes more than one-fifth of the direct, collective funding that keeps NATO’s military and civilian operations on track.

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