how many counties have at least one silver medal?
18
col : rank | nation | gold | silver | bronze | total row 1 : 1 | france | 28 | 28 | 24 | 80 row 2 : 2 | romania | 16 | 3 | 5 | 24 row 3 : 3 | canada | 14 | 10 | 15 | 39 row 4 : 4 | quebec | 8 | 4 | 16 | 28 row 5 : 5 | morocco | 6 | 11 | 7 | 24 row 6 : 6 | tunisia | 4 | 7 | 1 | 12 row 7 : 7 | egypt | 2 | 5 | 4 | 11 row 8 : 8 | switzerland | 2 | 1 | 5 | 8 row 9 : 9 | senegal | 2 | 1 | 3 | 6 row 10 : 10 | french community of belgium | 1 | 3 | 6 | 10 row 11 : 11 | madagascar | 1 | 2 | 3 | 6 row 12 : 12 | burkina faso | 1 | - | 2 | 3 row 13 : 13 | togo | 1 | - | 1 | 2 row 14 : 14 | guinea | 1 | - | - | 1 row 15 : 15 | lebanon | 1 | - | - | 1 row 16 : 16 | ivory coast | - | 3 | 3 | 6 row 17 : 17 | republic of the congo | - | 3 | 2 | 5 row 18 : 18 | new brunswick | - | 1 | 2 | 3 row 19 : 19 | central african republic | - | 1 | - | 1 row 20 : 20 | dominica | - | 1 | - | 1 row 21 : 21 | gabon | - | 1 | - | 1 row 22 : 22 | mali | - | 1 | - | 1 row 23 : 23 | cambodia | - | - | 2 | 2 row 24 : 24 | luxembourg | - | - | 2 | 2 row 25 : 25 | mauritius | - | - | 2 | 2 row 26 : 26 | burundi | - | - | 1 | 1 row 27 : 27 | djibouti | - | - | 1 | 1 row 28 : 28 | vietnam | - | - | 1 | 1
how many counties have at least one silver medal?
Rank Nation Gold Silver Bronze Total
1 France 28 28 24 80
2 Romania 16 3 5 24
3 Canada 14 10 15 39
4 Quebec 8 4 16 28
5 Morocco 6 11 7 24
6 Tunisia 4 7 1 12
7 Egypt 2 5 4 11
8 Switzerland 2 1 5 8
9 Senegal 2 1 3 6
10 French Community of Belgium 1 3 6 10
11 Madagascar 1 2 3 6
12 Burkina Faso 1 - 2 3
13 Togo 1 - 1 2
14 Guinea 1 - - 1
15 Lebanon 1 - - 1
16 Ivory Coast - 3 3 6
17 Republic of the Congo - 3 2 5
18 New Brunswick - 1 2 3
19 Central African Republic - 1 - 1
20 Dominica - 1 - 1
21 Gabon - 1 - 1
22 Mali - 1 - 1
23 Cambodia - - 2 2
24 Luxembourg - - 2 2
25 Mauritius - - 2 2
26 Burundi - - 1 1
27 Djibouti - - 1 1
28 Vietnam - - 1 1
18