Script to find Overall Code Coverage of Salesforce Org

OverAllCodeCoverageScript

HttpRequest req = new HttpRequest();
req.setHeader('Authorization', 'Bearer ' + UserInfo.getSessionID());
req.setHeader('Content-Type', 'application/json');
String domainUrl=URL.getSalesforceBaseUrl().toExternalForm();
system.debug('********domainUrl:'+domainUrl);
req.setEndpoint(domainUrl+'/services/data/v43.0/tooling/query/?q=SELECT+PercentCovered+FROM+ApexOrgWideCoverage');
req.settimeout(12000);
req.setMethod('GET');

Http h = new Http();
HttpResponse res = h.send(req);
string resBody = res.getBody();
system.debug(res.getBody());

string overAllCodeCoveragePercentage;

JSONParser  parser = JSON.createParser(resBody);
while (parser.nextToken() != null) {
	String fieldName = parser.getText();
	
	if(fieldName == 'PercentCovered') {
		parser.nextToken();
		overAllCodeCoveragePercentage = parser.getText();
		break;
	}
}
system.debug('*******overall Code Coverage:'+overAllCodeCoveragePercentage);