How important was the Marshall Plan in bringing about the recovery of Western Europe between 1947 and 1951?

Marshall Plan was announced in June 1947. It was an economic extension of Truman Doctrine. It was named after American Secretary of State George Marshall who forwarded his European Recovery Program, which offered financial and economic help wherever it was needed. This plan he said was not against any country or doctrine but against poverty, hunger, desperation and chaos. Western Europe was, in fact, suffering from all these problems and on the top of it, the region was also experiencing coldest winter in 70 years. One of the aims of Marshall plan was to promote economic recovery of Europe. By September, 16 nations (West Germany, Switzerland, Denmark, Sweden, Norway, Iceland, Turkey, Greece, Austria, Portugal, the Netherland, Luxemburg, Belgium, Italy, France and Britain) had drawn a joint plan to use American aid. In next four years, 13 billion flowed into Western Europe. It helped in the recovery of agriculture and industries.
Many historians claimed that Marshall Plan saved Europe from impending political and economic disaster. However, according to many European historians, this is not true. They say that European economies recovered so quickly that the conditions of recovery must already have been in place. Also, 13 billion looks a lot but in reality, Marshall plan aid constituted an average of 2.5 percent of the national income of 16 countries. 
Thus, we can say that Marshall Plan was helpful for the European economies but their recoveries were not solely based on Marshall Plan aid.