This is not an answer. This Code may help you prepare your input boxes.

Panel[
country = 0;
sector = 0;
level = 0;
result = {};
While[Not[IntegerQ[country] && 1 <= country <= 64], (country = Input["Which country do you want to analyze?"])];
While[Not[IntegerQ[sector] && 1 <= sector <= 15], (sector = Input["Which sector do you want to target?"])];
While[Not[NumericQ[level] && 0.01 <= level <= 1], (level = Input["At what significance level do you want to analyze IO matrix?"])];
result = {country, sector, level};
If[
 result === {}, "",
 ]
]

This is not an answer. This Code may help you prepare your input boxes.

Panel[
country = 0;
sector = 0;
level = 0;
result = {};
While[Not[IntegerQ[country] && 1 <= country <= 64], (country = Input["Which country do you want to analyze?"])];
While[Not[IntegerQ[sector] && 1 <= sector <= 15], (sector = Input["Which sector do you want to target?"])];
While[Not[NumericQ[level] && 0.01 <= level <= 1], (level = Input["At what significance level do you want to analyze IO matrix?"])];
result = {country, sector, level};
If[
 result === {}, "", result
 ]
]