Edit in JSFiddle

const request = new XMLHttpRequest();
request.open("GET", "https://api.datacommons.org/stat/value?place=country%2FGMB&stat_var=Amount_EconomicActivity_ExpenditureActivity_EducationExpenditure_Government_AsFractionOf_Amount_EconomicActivity_GrossDomesticProduction_Nominal&scalingFactor=100.0000000000", false /* async */ );
request.send();

if (request.status == 200) {
  let result = JSON.parse(request.responseText);
  console.log(result);
  document.getElementById("result").innerText = result["value"];
} else {
  console.log("There was an error fetching data.");
}

<p>
  The percentage of nominal GDP spent by the government of <a href="https://api.datacommons.org/stat/value?place=country%2FGMB&stat_var=Amount_EconomicActivity_ExpenditureActivity_EducationExpenditure_Government_AsFractionOf_Amount_EconomicActivity_GrossDomesticProduction_Nominal&scalingFactor=100.0000000000">the Gambia</a> on education: <span id="result"></span>
</p>