How many countries that allow same-sex marriage ?

By 2017, there are 28 countries that legalize same-sex marriage, they are:

1 The Netherlands (2000)
2 Belgium (2003)
3 Canada (2005)
4 Spain (2005)
5 South Africa (2006)
6 Norway (2008)
7 Sweden (2009)
8 Argentina (2010)
9 Iceland (2010)
10 Portugal (2010)
11 Denmark (2012)
12 Brazil (2013)
13 England (2013)
14 Wales (2013)
15 France (2013)
16 Uruguay (2013)
17 New Zealand (2013)
18 Luxembourg  (2014)
19 Scotland (2014)
20 Finland (2015)
21 Greenland (2015)
22 Ireland (2015)
23 United States (2015)
24 Colombia (2016)
25 Australia (2017)
26 Germany (2017)
27 Malta (2017)
28 Taiwan (2017)