Help on parsing Xml

I am trying to parse the next xml

Euro Bank Rate change

whatever I do I can't get the the rate for USA I get that the node is null for example :

var nsmgr = new XmlNamespaceManager(xmlDocument.NameTable);
            nsmgr.AddNamespace("gesmes", "http://www.gesmes.org/xml/2002-08-01");
            XmlNode node = xmlDocument.SelectSingleNode("/gesmes:Envelope[@xmlns:gesmes=\"http://www.gesmes.org/xml/2002-08-01\"]/Cube/Cube[@time=\"2019-12-18\"]//Cube[1]", nsmgr);
            XmlNodeList nodes = xmlDocument.SelectNodes("//gesmes:Cube", nsmgr);
            XmlNodeList n2odes = xmlDocument.SelectNodes("/gesmes:Envelope/Cube/Cube/Cube", nsmgr);