This is based on many factors. Including starting GDP, surplus/ deficit, production, actual use and population. Look out for updates and check out my military ranking guide.
http://steamproxy.com/sharedfiles/filedetails/?id=190060716

Super Power Tier
(The three largest and most powerful economies in the world. If anyone of them stopped production the world economy would crash.)
1. United States
2. China
3. USSR

Great Power Tier
(These nations could catch up to the super powers, if played well. They all are very large producers.)
4. United Kingdom
5. Japan
6. India
7. France
8. West Germany
9. Italy
10. Canada

Power Tier
(Better than average economies. If played well, these nations can become very powerful.)
11. Mexico
12. Brazil
13. Indonesia
14. Spain
15. Argentina
16. Poland
17. Australia
18. Netherlands
19. Belgium
20. Iran
21. Venezuela
22. Pakistan
23. East Germany
24. Sweden
25. Czechoslovakia
26. Turkey

Third World Power Tier
(These nations out class many third world nations. In 5 or so years they can become very powerful.)
27. Yugoslavia
28. Switzerland
29. Colombia
30. Philippines
31. Austria
32. Hungary
33. Romania
34. Egypt
35. South Africa
36. South Korea
37. Thailand
38. Denmark
39. Chile
40. Peru
41. Portugal
42. Burma
43. Taiwan
44. Greece
45. Finland
46. Bulgaria
47. Ethiopia
48. North Korea
49. North Vietnam

Third World Tier
(These nations are all very behind the curve. They lack industrial and electrical autarky and constructing new buildings is very hard with them.)
50. Cuba
51. Ceylon
52. Saudi Arabia
53. Ecuador
54. Jordan
55. Ireland
56. Uruguay
57. Iraq
58. Syria
59. Norway
60. New Zealand
61. Bolivia
62. Guatemala
63. Nepal
64. Afghanistan
65. Lebanon
66. Dominican Republic
67. Israel
68. El Salvador
69. Haiti
70. Saarland
71. North Yemen
72. Paraguay
73. Panama
74. Honduras
75. Luxembourg
76. Costa Rica
77. Albania
78. Mongolia
79. Liberia
80. Muscat & Oman
81. Nicaragua
82. Iceland
83. Bhutan
84. Andorra