Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Volume | Year | Names | Articles | Pages | Images | Maps | Number of copies |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 1974 | Ա-ԱՐԳԻՆԱ | 3,442 | 720 | 1,294 | 75 | 100,000 |
| 2 | 1976 | ԱՐԳԻՇՏԻ-ԳԵՂԵՐՎԱՆ | 3,503 | 720 | 1,798 | 75 | 100,000 |
| 3 | 1977 | ԳԵՂԵՑԻԿԸ-ԶՈՒՐԱԲՅԱՆ | 3,509 | 720 | 1,726 | 53 | 100,000 |
| 4 | 1978 | Է-ԽԱՂԽԱՂ | 3,451 | 720 | 1,228 | 53 | 100,000 |
| 5 | 1979 | ԽԱՂՈՂ-ԿՈՒԼԻՍՆԵՐ | 3,694 | 720 | 1,326 | 68 | 100,000 |
| 6 | 1980 | ԿՈՒԼԶՈՐ-ՁՈՒԼՈՒԿ | 3,108 | 720 | 1,097 | 64 | 100,000 |
| 7 | 1981 | ՁՈՒԼՈՒՄ-ՄՈՆՈՊԽՈՆՔ | 3,250 | 720 | 1,436 | 46 | 100,000 |
| 8 | 1982 | ՄՈՆՈՊՈԼԻԱ-ՉԵՉԵՐԵԿ | 3,145 | 720 | 1,274 | 70 | 100,000 |
| 9 | 1983 | ՉԵՉՔԱՐ-ՌՍՏԱԿԵՍ | 3,185 | 720 | 1,046 | 60 | 100,000 |
| 10 | 1984 | ՌՍՏԱՄ-ՍՍՀՄ | 2,009 | 736 | 1,065 | 61 | 100,000 |
| 11 | 1985 | ՍՈՎԵՏԱԿԱՆ-ՏԻԵԶԵՐՔ | 2,970 | 720 | 958 | 67 | 100,000 |
| 12 | 1986 | ՏԻԵՊՈԼՈ-ՖՈՒՔՍԻՆ | 3,501 | 752 | 1,015 | 96 | 100,000 |
| TOTAL (1–12) | 1974–1986 | Ա-ՖՈւՔՍԻՆ | 36,767 | 8,688 | 15,263 | 858 | 1,200,000 |
| 13 | 1987 | ՍՈՎԵՏԱԿԱՆ ՀԱՅԱՍՏԱՆ |  |  |  |  |  |
Question:
what is the difference in years between the first volume published and the 13th volume published?
Answer:
13